Shaft sealing device and valve structure using the same

ABSTRACT

A shaft sealing device with a simple internal structure switches a sealing state and an unsealing state of a fluid, with high sealing performance maintained, because of no abrasion accompanying the movement of a sealing material or a sealing member, thereby enabling feeding a fluid at a predetermined flow rate, and adjusts the expanding rate of the sealing material with the quantity of an external electric signal and accordingly adjusts the contact face pressure to enable controlling the amount of leakage of the fluid highly precisely, so that it can be used for all applications. The shaft sealing device includes a shaft sealing body formed of a macromolecular material and made expansible or contractible, or deformable, through external electrostimuli applied to a shaft sealing portion disposed in a device body, and flow passages disposed in the shaft sealing portion for feeding the fluid leaked due to the expansion or contraction, or the deformation, of the shaft sealing body.

TECHNICAL FIELD

The present invention relates to a shaft sealing device forshaft-sealing a fluid using a sealing member and, particularly, to ashaft sealing device using an electro stimuli-responsive macromolecularmaterial and to a valve structure using the same.

BACKGROUND ART

Generally, in the case of sealing a fluid in a container at all times, ashaft sealing device using a sealing member is utilized. The shaftsealing device is intended to seal the flow of the fluid via the sealingmember. As the sealing member of the shaft sealing device, an annularO-ring or packing substantially circular in cross section, for example,is used in order to seal a wide variety of fluids including air, water,oil and gas. The sealing member is required to have high sealingperformance because the principal function thereof is to seal thefluids.

For this reason, the sealing member is axially attached to a groove of asubstantially rectangular shape in cross section formed within the sameplane in the radial direction of a shaft or hole of one of members inthe shaft sealing device and, when attaining a seal by pressure ofcontact with the other of the members in the shaft sealing device, iscompressed by the shape of the groove. It is therefore required to havea compression allowance. After the assemblage of the shaft sealingdevice, the O-ring, for example, is compressed via the compressionallowance to produce a repulsion force and, by the repulsion force,fulfills contact surface pressure sealability to attain a shaft seal.

In addition, the O-ring is generally made from one of various kinds ofsynthetic rubber materials. In order to fulfill an appropriatecompression stress within a range in which extraordinary deformation isnot induced, the material is required to have a prescribed lowcompression set and further satisfy characteristics includingantiweatherability, abrasion resistance, heat resistance, coldresistance, oil resistance and chemical resistance. In addition, sinceO-rings are used in shaft sealing devices over a wide variety of fieldsincluding fields of automobiles, constructing machines, airplanes,office automation equipment and industrial instruments, for example, thematerial for the O-rings is selected to have an appropriate compressionallowance in accordance with an intended field (purpose) and, even whenbeing used in either a state accompanying the movement of a shaftsealing portion or a stationary state not accompanying the movement ofthe shaft sealing portion, fulfills durability, insertability andpressing crack prevention, not to mention securement of a shaft-sealingfunction. Thus, an ordinary shaft sealing device aims first at enhancinga sealing function with a sealing member, such as an O-ring. Generally,therefore, a sealing region of the sealing member or fluid is determinedat a prescribed location. An apparatus having such a sealing deviceembedded therein has a complicated internal structure.

Assuming now that it is necessary to switch the sealing region to anunsealing region, a section of attachment of a sealing member or housingin the sealing region has to be provided with a separate movingmechanism in order to move the sealing region. The moving mechanismincludes a screw feed mechanism, a piston-cylinder mechanism and arotating mechanism, for example. In order to operate these mechanisms,it is necessary to use some power means, such as human power,electricity, air, hydraulic pressure, spring, etc.

On the other hand, not a sealing mechanism, but a valve using aso-called artificial muscle and having no complicated power means isdisclosed (refer to Patent Document 1, for example). This valve uses anartificial muscle as a valving element and deforms the valving elementper se to enable opening and closing a flow path. The valve disclosed inthe Document uses as the valving element the artificial muscle formed ofan electrostrictive elastic polymer film and deforms the valving elementthrough a voltage ON-OFF operation to bring the valving element intocontact with and separation from a valve seat, thereby opening andclosing the flow path. The artificial muscle in this valve is called anEPAM (Electroactive Polymer Artificial Muscle) comprising a thinrubber-like macromolecular film (elastomer) and elastic electrodessandwiching the film, in which voltage is applied between the electrodesto elongate the macromolecular film in a plane direction (todiameter-enlarge it in a circumferential direction).

Patent Document 1: Japanese Patent No. 3,501,216

DISCLOSURE OF THE INVENTION Problems the Invention Intends to Solve

However, the case where the shaft sealing device is provided with amoving mechanism or power means in order to switch the sealing region tothe unsealing region has entailed a problem that the device becomescomplicated in structure and large in entire size. For this reason, thedevice has possibly been increased in weight and manufacturing cost. Inaddition, since switching between the sealed state and the unsealedstate has accompanied mutual contact and sliding motion among partsconstituting the moving mechanism, the contact and sliding motion haspossibly caused the parts constituting the moving mechanism and thesliding members to abrade away. Furthermore, since a seal material ismoved in a state of contact with and pressure application to acounterpart sealing member within the sealing region, abrasionaccompanying the sliding motion has been induced. When a sealing portionincluding an O-ring has induced abrasion over the entire circumferencethereof, fluid leakage is liable to generate due to the pressurereduction at or damage on a contact portion and, in this case, abrasionhas further been induced due to external factors including a coarsesliding surface and insufficient lubrication. Moreover, the fluidleakage is liable to generate even when the sliding surface of theO-ring has been abraded away and, when the sliding surface of the O-ringhas had scratches, abrasion is further been induced. Particularly, inthe case where the motion speed of the moving mechanism has been rapid,where the movement has been made in an eccentric state, where the planeroughness of the sliding surface has been large or where the lubricationhas been insufficient, the seal material has possibly been twisted.

Furthermore, since a noise is possibly generated due to the contact orsliding motion of the seal material, sealing member or moving mechanismor since a new task of using a lubricant in order to prevent this noiseor abrasion is possibly necessitated, the shaft sealing device hasentailed a problem that the reliability thereof at the time of sealingis lowered or that the durability life thereof is considerablyshortened.

In addition, though the shaft sealing device is configured so as tofulfill high sealing performance through the securement of precision inplane coarseness of the sealing member in the sealing region, throughthe attainment of sealing the fluid by the pressure of contact of theseal material with the counterpart member induced in consequence ofcompressing the compression allowance and through the increase inpressure of contact (self-sealing function) due to the compression ofthe compression allowance in addition to the deformation of the sealmaterial accompanying the compression, thereby fulfilling contactsurface pressure higher than the fluid pressure, it has generally beenknown that even in the case of the shaft sealing device, it is difficultto completely prevent fluid leakage because a phenomenon of entrainingthe fluid accompanying the movement of the sealing portion occurs.Furthermore, since an acceptable range of the amount of fluid leakage atthe time of shaft sealing has been set in accordance with an intendedpurpose of a shaft sealing device and since the shaft sealing device isgenerally required to perform shaft seal while maintaining the amount offluid leakage within the set acceptable range, the amount of fluidleakage becomes difficult to control.

On the other hand, though Patent Document 1 uses the EPAM as the valvingelement to eliminate any complicated power mechanism, since the valvingelement per se constitutes the EPAM and since the fluid pressure isreceived on the pressure-receiving area of the entire EPAM at the timeof fluid sealing, the EPAM is required to have both large compressionstrength and large sealing power. In addition, since it is necessary toprovide a separate sealing mechanism in a main body and prepare a valveseat portion for seating, the application of the EPAM to the valvingelement per se is irrationalistic because the strength resistance andstress characteristics accompanying deformation the EPAM has are notutilized as-is. Particularly, Patent Document 1 neither has any idea orsuggestion in respect of the point of the present inventors' observationthat an EPAM is applied to a shaft sealing structure per se nor has anyidea or suggestion with respect to the fact that an increase anddecrease in shaft sealing power is subtly adjusted with high precisionby the function of the EPAM to utilize a fluid leakage phenomenonincluding minute leakage.

The present inventors have reached the development of the presentinvention as a consequence of keen studies made in view of theconventional state of affairs described above. The object of the presentinvention is to provide a shaft sealing device with a simple internalstructure that switches a sealing state and an unsealing state of afluid, with high sealing performance maintained, because of no abrasionaccompanying the movement of a sealing material or a sealing member,thereby enabling feeding a fluid at a predetermined flow rate, andadjusts the expanding rate of the sealing material with the quantity ofan external electric signal and accordingly adjusts the contact facepressure to enable controlling the amount of leakage of the fluid highlyprecisely, so that it can be used for all applications, and to provide avalve structure using the shaft sealing device.

Means for Solving the Problems

To attain the above object, the invention of claim 1 relates to a shaftsealing device comprising a device body, a shaft sealing portiondisposed in the device body, a shaft sealing body formed of amacromolecular material and made expansible or contractible, ordeformable, through external electro stimuli applied to the shaftsealing body and flow passages disposed in the shaft sealing portion forfeeding a fluid leaked due to expansion or contraction, or deformation,of the shaft sealing body.

The invention of claim 2 relates to the above shaft sealing device,wherein the shaft sealing body is formed of an electrostimuli-responsive macromolecular material that is subjected to enlargeddeformation in a direction orthogonal to a voltage application directionwhen having been charged with external electro stimuli, therebyheightening shaft sealing power whereas the electro stimuli-responsivemacromolecular material is returned to an original position while beingsubjected to contracted deformation in the direction orthogonal to thevoltage application direction when having been discharged, therebyinducing an appropriate leakage phenomenon due to a decrease in shaftsealing power, or that is returned to the original position while beingsubjected to the enlarged deformation in the direction orthogonal to thevoltage application direction when having been discharged, therebyheightening the shaft sealing power whereas the electrostimuli-responsive macromolecular material is lowered in shaft sealingpower while being subjected to contracted deformation in the directionorthogonal to the voltage application direction when having been chargedwith the external electro stimuli, thereby inducing the appropriateleakage phenomenon.

The invention of claim 3 relates to the first mentioned shaft sealingdevice, wherein the shaft sealing body is formed of an electroconductivemacromolecular material that is returned to original position whilebeing expanded when application of external electro stimuli has beenstopped, thereby heightening shaft sealing power, whereas theelectroconductive macromolecular material is lowered in shaft sealingpower while being shrunk when the external electro stimuli have beenapplied, or that is heightened in shaft sealing power while beingexpanded when the external electro stimuli have been applied, whereasthe electroconductive macromolecular material is returned to theoriginal position while being shrunk when the application of theexternal electro stimuli have been stopped, thereby inducing anappropriate leakage phenomenon due to a decrease in shaft sealing power.

The invention of claim 4 relates to the first mentioned shaft sealingdevice, wherein the shaft sealing body is formed of an ionicallyconductive macromolecular material that is returned to an originalposition while being deformed when application of external electrostimuli has been stopped, thereby heightening shaft sealing power,whereas the ionically conductive macromolecular material is deformedwhen the external electro stimuli have been applied, thereby inducing anappropriate leakage phenomenon due to a decrease in shaft sealing power,or that is heightened in shaft sealing power while being deformed whenthe external electro stimuli have been applied, whereas the ionicallyconductive macromolecular material is returned to the original positionwhile being deformed when the application of the external electrostimuli has been stopped, thereby inducing the appropriate leakagephenomenon due to a decrease in shaft sealing power.

The invention of claim 5 relates to the first mentioned shaft sealingdevice, wherein the shaft sealing body is formed of an electrostimuli-responsive macromolecular material that is returned to anoriginal position while being deformed when application of externalelectro stimuli has been stopped, thereby heightening shaft sealingpower, whereas the electro stimuli-responsive macromolecular materialhas deformed a section thereof other than a section thereof to which theexternal electro stimuli have been applied, thereby inducing anappropriate leakage phenomenon due to a decrease in shaft sealing power.

The invention of claim 6 relates to the first mentioned shaft sealingdevice, wherein the shaft sealing body is formed of an electrostimuli-responsive macromolecular material that deforms, when externalelectro stimuli have been applied, a section thereof other than asection thereof to which the external electro stimuli have been applied,thereby heightening shaft sealing power, whereas the electrostimuli-responsive macromolecular material is returned to an originalposition while being deformed when application of the external electrostimuli has been stopped, thereby inducing an appropriate leakagephenomenon due to a decrease in shaft sealing power.

The invention of claim 7 relates to any one of the first to fourthmentioned shaft sealing devices, further comprising a holder capable ofretaining the shaft sealing body on a retaining surface thereof fromupper and lower directions and electrodes which are provided on theretaining surface of the holder and which are electrically connected toan exterior of the device body.

The invention of claim 8 relates to any one of the first, fifth andsixth mentioned shaft sealing devices, wherein the shaft sealing body isprovided with electrodes which are connected to an exterior of thedevice body in a state clamping part of upper and lower surfaces of theshaft sealing body.

The invention of claim 9 relates to any one of the first to sixthmentioned shaft sealing devices, wherein the shaft sealing bodycomprises at least two shaft sealing bodies disposed in the device bodyand the flow passages comprise at least three leaked-fluid flow passagesdisposed in the device body, and further comprising a holder capable ofretaining the shaft sealing bodies, respectively, on a retaining surfacethereof from upper and lower directions and electrodes which areprovided on the retaining surface of the holder and which areelectrically connected to an exterior of the device body, whereinapplication and stop of application of external electro stimuli to theshaft sealing bodies from the electrodes makes the shaft sealing bodiesexpansible or contractible, or deformable, to make the flow passagesswitchable.

The invention of claim 10 relates to any one of the second to ninthmentioned shaft sealing devices, wherein the leakage phenomenon includesa minute leakage phenomenon.

The invention of claim 11 relates to a shaft sealing device comprising adevice body, a holder, and an annular shaft sealing body which isinserted into the device body via the holder, which has a base fixed tothe holder or device body and a distal free end serving as a shaftsealing portion and which allows the shaft sealing portion to expand orcontract in a substantially perfectly circular shape when externalelectro stimuli have been applied thereto, thereby obtaining a shaftsealed state or a fluid leaking state.

The invention of claim 12 relates to the above shaft sealing device,wherein the shaft sealing body comprises a plate-like annular basematerial which is formed of a macromolecular material made expansible orcontractible, or deformable, through external electro stimuli applied tothe shaft sealing body and which has front and back surfaces providedrespectively with electrodes.

The invention of claim 13 relates to the eleventh mentioned shaftsealing device, wherein the shaft sealing body comprises a hollowcylinder which is formed of a macromolecular material made expansible orcontractible, or deformable, through external electro stimuli applied tothe shaft sealing body and which has inner and outer circumferentialsurfaces provided integrally with electrodes, respectively.

The invention of claim 14 relates to a valve structure using any one ofthe eleventh to thirteenth mentioned shaft sealing device, wherein thedevice body is formed with plural flow passages communicating with anexterior of the device body, and the shaft sealing portion that is thefree end of the shaft sealing body is disposed between adjacent flowpassages so as to be brought to a shaft sealed state or a fluid leakingstate, thereby making the flow passages switchable.

The invention of claim 15 relates to the above valve structure, whereinthe shaft sealing body has a base near a substantially central partthereof and opposite free ends serving as shaft sealing portions thatpermit contact with or separation from at least two inner cylindricalannular portions, thereby making the flow passages switchable.

The invention of claim 16 relates to the fourteenth mentioned valvestructure, wherein the shaft sealing body comprises at least two shaftbodies which are disposed in the device body and each of which has afree end serving as a shaft sealing portion brought to a shaft sealedstate or a fluid leaking state.

EFFECTS OF THE INVENTION

According to the invention of claim 1, it is possible to provide a shaftsealing device with a simple internal structure that switches a sealingstate and an unsealing state of a fluid, with high sealing performancemaintained, because of no abrasion accompanying the movement of a shaftsealing body, thereby enabling feeding a fluid at a predetermined flowrate, and adjusts the amount of expansion or contraction, or the amountof deformation, of the shaft sealing body with the quantity of anexternal electric signal and accordingly adjusts the contact facepressure to enable controlling the amount of leakage of the fluid highlyprecisely, so that it can be used for all applications. In addition,since the shaft sealing body can be deformed in the absence of a movingmechanism to enable preventing the inside of the shaft sealing devicefrom being deteriorated, the shaft sealing device can fulfill anexcellent shaft sealing function over a long period of time. As aresult, the shaft sealing device of the present invention can beutilized as a substitute for an electromagnetic valve and, further sincethe amount of minute leakage in a shaft sealed state can be controlled,utilized in various technical fields.

According to the invention of claim 2, since only the shaft sealing bodycan be increased or decreased in diameter through performing or stoppingthe application of the external electro stimuli, it is possible toswitch between the sealed state and the unsealed state while preventingdeterioration of the device body through keeping the movable portion ofthe device body to the minimum. In the sealed state, the shaft sealingdevice can heighten the shaft sealing power to fulfill the excellentsealability and, in the unsealed state, can flow a fluid at a constantflow rate, with the amount of leakage peculiar to the device body as theflow rate. In this case, furthermore, the shaft sealing device allowsthe shaft sealing body to have an EPAM structure that can enlarge thepressure or distortion amount during the operation to enable a highershaft sealing function to be fulfilled, allows the device body to have alight weight because of the simple structure and allows the soundgenerated to be quiet.

According to the inventions of claims 3 to 6, it is possible to providethe shaft sealing device, in which various macromolecular materials areused to enable the configuration of the shaft sealing body and theprovision of the shaft sealing structure made appropriate in accordancewith the macromolecular materials different in expansion or contraction,or deformation, of the shaft sealing portion. Also in this case,excellent functionality in the time of sealing or unsealing can befulfilled similarly in the case of the provision of the EPAM structure.Of these inventions, according to the inventions of claims 5 and 6 inparticular, it is possible to provide the shaft sealing device, in whichsince the section other than the section to which the external electrostimuli have been applied is deformed, it is unnecessary provide thesection with electrodes and, since the deformed portion is the free end,it is possible to make the deformation amount large. For these reasons,it is possible to provide the shaft sealing device capable of acquiringa large amount of leakage flow rate and controlling the flow rate withhigh precision.

According to the invention of claim 7 or 8, since it becomes possible tocontrol the voltage applied from the exterior of the device body to theshaft sealing body, it is possible to provide the shaft sealing devicecapable of applying the device body to a small-sized device orinstrument and downsizing a space occupied by the shaft sealing deviceand thus being utilized at various places.

According to the invention of claim 9, it is possible to provide theshaft sealing device that can be used as a flow passage switching valveand applied to various switching mechanisms including a piston-cylindermechanism, for example and, also in this case, control thepiston-cylinder operation speed with high precision.

According to the invention of claim 10, since minute leakage in theshaft sealed state can be controlled, it is possible to provide theshaft sealing device capable of making a control of a minuter leakageamount in addition to a control of a leakage amount of an ordinary fluidflowing.

According to the invention of claim 11, the shaft sealing device has ashaft sealing structure capable of expanding or contracting the free endof the shaft sealing body in a perfectly circular shape relative to theinner circumferential surface of the device body while maintaining highprecision and controlling the shaft sealing body in the shaft sealedstate or fluid leakage state on the primary and secondary sides throughthe circumferential surface of the shaft sealing body coming intocontact with or separating from the cylindrical flow passage and cantherefore be applied to various kinds of flow passages.

According to the invention of claim 12, since only the shaft sealingbody can be expanded or contracted through performing or stopping theapplication of the external electro stimuli, it is possible to switchbetween the sealed state and the unsealed state while preventingdeterioration of the device body through keeping the movable portion ofthe device body to the minimum. In the sealed state, the shaft sealingdevice can heighten the shaft sealing power to fulfill the excellentsealability and, in the unsealed state, can flow a fluid at a constantflow rate, with the amount of leakage peculiar to the device body as theflow rate.

According to the invention of claim 13, it is possible to provide theshaft sealing device having the effects, in addition of the effects ofclaim 12, of reducing the distortion of the shaft sealing body after theintegral formation of the shaft sealing body in the shape of a ring andmaking the control of the shaft sealed state or fluid leaking state withhigher precision.

According to the inventions of claims 14 and 16, it is possible toprovide the valve structure using the valve sealing device capable ofmaking the structure of the shaft sealing simple and compact and beingutilized as a switching valve of a structure which can switch pluralflow passages and which has not existed conventionally. In addition,since the number of the flow passages can be increased in accordancewith embodiments and, even in the case of adopting the multiway valvestructure, each flow passage can be brought to the prescribed shaftsealed state or fluid leakage state while controlling the shaft sealedstate or fluid leakage state with high precision, the valve structurehaving the shaft sealing device can be controlled as the multiway valveand utilized in various fields.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross section showing one example of a shaft sealing deviceaccording to the present invention.

FIG. 2 is a plan view of FIG. 1.

FIG. 3 is a cross section showing a shaft sealed state of the shaftsealing device of FIG. 1.

FIG. 4 includes top perspective views showing one example of a sealingmember, (a) being an exploded perspective view of the sealing member and(b) being a perspective view showing an assembled state of the sealingmember.

FIG. 5 includes bottom perspective views showing the example of thesealing member, (a) being an exploded perspective view of the sealingmember and (b) being a perspective view showing an assembled state ofthe sealing member.

FIG. 6 is a cross section showing another example of the shaft sealingdevice according to the present invention.

FIG. 7 is a plan view of FIG. 6.

FIG. 8 is a cross section showing a movement state of the shaft sealingdevice of FIG. 6.

FIG. 9 includes top perspective views showing a different example of thesealing member, (a) being an exploded perspective view of the sealingmember and (b) being a perspective view showing an assembled state ofthe sealing member.

FIG. 10 includes bottom perspective views showing the different exampleof the sealing member, (a) being an exploded perspective view of thesealing member and (b) being a perspective view showing an assembledstate of the sealing member.

FIG. 11 is a perspective view showing the shape of a holder.

FIG. 12 is a schematic view showing an example in which the shaftsealing device of the present invention is applied to a safety valve.

FIG. 13 includes schematic views showing an example in which the shaftsealing device of the present invention is applied to a piston-cylinderdrive mechanism.

FIG. 14 is an explanatory view showing the characteristics of an electrostimuli-responsive macromolecular material, electroconductivemacromolecular material and ionically conductive macromolecular materialused in the present invention.

FIG. 15 is an explanatory view showing the characteristics of theelectro stimuli-responsive macromolecular material which is used in thepresent invention and which, when having been subjected to externalelectro stimuli, has a section thereof, other than a section thereof towhich the external electro stimuli have been applied, deformed.

FIG. 16 includes schematic views showing the movement made when anelectric field has been applied to the electro stimuli-responsivemacromolecular material which, when having been subjected to externalelectro stimuli, has a section thereof, other than a section thereof towhich the external electro stimuli have been applied, deformed, (a)being a schematic view showing the distribution of the electric fieldapplied to the electro stimuli-responsive macromolecular material, (b)being a schematic view showing a state of a stress generated on theelectro stimuli-responsive macromolecular material and (c) being aschematic view showing a state in which the electro stimuli-responsivemacromolecular material has been deformed.

FIG. 17 includes cross sections showing a shaft sealing device in whicha shaft sealing body made of an electro stimuli-responsivemacromolecular material has been retained by a holder.

FIG. 18 includes cross sections showing a shaft sealing device in whicha shaft sealing body made of an electroconductive macromolecularmaterial has been retained by a holder.

FIG. 19 includes cross sections showing a shaft sealing device in whicha shaft sealing body made of an ionically conductive macromolecularmaterial has been retained by a holder.

FIG. 20 includes cross sections showing a shaft sealing device in whicha shaft sealing body made of a macromolecular material has been retainedby a holder.

FIG. 21 includes cross sections showing a state in which a separator hasbeen attached to the shaft sealing device of FIG. 17.

FIG. 22 includes cross sections showing a state in which a separator hasbeen attached to the shaft sealing device of FIG. 18.

FIG. 23 is an explanatory view showing the characteristics of amacromolecular material used for a valve structure.

FIG. 24 includes cross sections showing a shaft sealing device in whicha shaft sealing body made of an electro stimuli-responsivemacromolecular material has been formed annularly.

FIG. 25 includes cross sections showing a shaft sealing device in whicha shaft sealing body made of an electroconductive macromolecularmaterial has been formed annularly.

FIG. 26 includes cross sections showing another example of the shaftsealing device in which a shaft sealing body made of anelectroconductive macromolecular material has been formed annularly.

FIG. 27 includes cross sections showing a shaft sealing device in whicha shaft sealing body made of an ionically conductive macromolecularmaterial has been formed annularly.

FIG. 28 is a cross section showing one example of a valve structureusing a shaft sealing device.

FIG. 29 is a cross section showing a sealed state of the valve structureof FIG. 28.

FIG. 30 includes explanatory views showing a state of development of theshaft sealing body of FIG. 28, (a) being a schematic perspective view ofthe shaft sealing body, (b) being a development view showing the frontside of (a) and (c) being a development view showing the back side of(a).

FIG. 31 is a cross section showing a different example in which thevalve structure using the shaft sealing device has been applied to amultiway valve.

FIG. 32 is a cross section showing a state in which a flow passage hasbeen switched in the valve structure of FIG. 31.

FIG. 33 includes explanatory views showing a state of development of theshaft sealing body of FIG. 31, (a) being a schematic perspective view ofthe shaft sealing body, (b) being a development view showing the frontside of (a) and (c) being a development view showing the back side of(a).

FIG. 34 is a cross section showing another example in which the valvestructure using the shaft sealing device has been applied to a multiwayvalve.

FIG. 35 is a cross section showing a state in which the flow passage hasbeen switched in the valve structure of FIG. 34.

FIG. 36 is a schematic perspective view showing a workpiece used in aCAE analysis.

FIG. 37 is a schematic perspective view showing another workpiece usedin the CAE analysis.

FIG. 38 is a schematic view showing one example of the workpiecedeformed in shape in consequence of the CAE analysis.

FIG. 39 a schematic view showing another example of the workpiecedeformed in shape in consequence of the CAE analysis.

FIG. 40 is a schematic view showing a displacement measuring device.

FIG. 41 includes graphs showing measurement results of measuringconditions and amounts of displacement by the displacement measuringdevice, (a) being a graph showing voltage application conditions, (b)being a graph showing a state of electric current at the time of voltageapplication and (c) being a graph showing the amount of displacement ofa measured body.

FIG. 42 includes schematic views showing a bend displacement portion ofa measured body, (a) being a schematic view showing the displacementportion of the measured body and (b) being an enlarged view of a portionE in (a).

EXPLANATION OF REFERENCE NUMERALS

-   -   10 Device body    -   15 Shaft sealing portion    -   20, 160 Shaft sealing bodies    -   13, 14 Leakage flow passages    -   40 Holder    -   41 Upper holder    -   41 c Retaining surface    -   45 Lower holder    -   45 c Retaining surface    -   50, 51 External electrodes    -   150 Device body    -   160 Shaft sealing body    -   161 Base material    -   162, 163 Electrodes    -   166 Base    -   167 Free end    -   170 Holder

BEST MODE FOR CARRYING OUT THE INVENTION

The shaft sealing device of the present invention will be describedhereinafter in detail with reference to the drawings. The shaft sealingdevice comprises a device body, a shaft sealing portion disposed in thedevice body, a shaft sealing body disposed in the shaft sealing portion,made of a macromolecular material and made expansible or contractible,or deformable, through outer electro stimuli, and flow passages whichare formed in the shaft sealing portion and on which a fluid leaked dueto the expansion or contraction, or the deformation, of the shaftsealing body. The expansion or contraction used herein in the presentinvention is defined by a change in shape of the shaft sealing bodyaccompanying a change in volume of the shaft sealing body, and thedeformation is defined by a change in shape of the shaft sealing bodyaccompanying no change in volume of the shaft sealing body.

The macromolecular material used in the present invention includes atleast four kinds of materials, one being an electro stimuli-responsivemacromolecular material (dielectric elastomer), another anelectroconductive macromolecular material, another an ionicallyconductive macromolecular material and the remainder an electrostimuli-responsive macromolecular material having deformed a sectionother than a section to which external electro stimuli have beenapplied. Here, the characteristics of each macromolecular material areshown in FIGS. 14 and 15.

When external electro stimuli have been applied to the shaft sealingbody using the electro stimuli-responsive macromolecular material, theshaft sealing body is expansion-deformed in the direction orthogonal tothe direction of the application to heighten shaft sealing power,whereas the shaft sealing body is returned to the original positionwhile being contraction-deformed in the direction orthogonal to theapplication direction when the application of the external electrostimuli has been stopped, thereby lowering the shaft sealing power toinduce an appropriate fluid leakage phenomenon. Thus, the shaft sealingdevice using the external electro stimuli forms flow passages whenapplying no current, i.e. makes a so-called normally open (NO) deviceoperation, and has the material body deformed as a mode of change madewhen flowing a leaked fluid. In this case, a potential difference isgiven (voltage is applied) to between compliant electrodes providedrespectively on the front and back surfaces of the elastomer material toreduce the material in the width direction by means of the Coulombeffect, thereby making a motion of expanding the material in the surfacedirection.

The shaft sealing body using the electroconductive macromolecularmaterial is returned to the original position while being expanded whenthe application of the exterior electro stimuli has been stopped,thereby heightening the shaft sealing power, whereas it is contracted tolower the shaft sealing power when the external electro stimuli havebeen applied thereto, thereby inducing an appropriate fluid leakagephenomenon. Thus, the shaft sealing device using the electroconductivemacromolecular material is brought to a shaft sealed state, i.e. aso-called normally closed (NC) device state, when applying no current,and has the material body expanded or contracted as a mode of changemade when a leaked fluid flows. In this case, a potential difference isgiven to the electroconductive macromolecular material, the materialbody is expanded or contracted through adsorption or desorption ofmoisture in the air.

The shaft sealing body using the ionically conductive macromolecularmaterial is returned to the original position while being deformed whenthe application of the exterior electro stimuli has been stopped,thereby heightening the shaft sealing power, whereas it is deformed tolower the shaft sealing power when the external electro stimuli havebeen applied thereto, thereby inducing an appropriate fluid leakagephenomenon. Thus, the shaft sealing device using the ionicallyconductive macromolecular material is brought to the NC device state andhas the material body expanded or contracted as a mode of change madewhen a leaked fluid flows. In this case, a potential difference is givento the ionically conductive macromolecular material, cations in thematerial body accompany moisture and move to the side of anions and, asa result, the material body has a lopsided water content to bend thematerial body.

The shaft sealing body using the electro stimuli-responsivemacromolecular material having deformed a section other than a sectionto which external electro stimuli have been applied, is returned to theoriginal position while being deformed when the application of theexternal electro stimuli has been stopped, thereby heightening the shaftsealing power, whereas the section other than the section to whichexternal electro stimuli have been applied is deformed to lower theshaft sealing power, thereby inducing an appropriate fluid leakagephenomenon. Thus, the shaft sealing device using this electrostimuli-responsive macromolecular material is brought to the NC devicestate and the material body is deformed as a mode of change made when aleaked fluid flows.

As one example of the electro stimuli-responsive macromolecularmaterial, for example, polyether urethane can be cited. This materialcomprises a mixture of a base compound and a curing agent. The basecompound includes at least styrene, a nitrile compound, BHT(butylhydroxytoluene) and ester phthalate. On the other hand, the curingagent includes at least phthalic acid, diphenylmethane di-isothianateand ester phthalate. As a concrete example of the electrostimuli-responsive macromolecular material containing these components,a gel sheet manufactured by EXSEAL Corporation and sold under the tradename Hitohada (registered trademark) can be raised, for example. Inaddition, the electro stimuli-responsive macromolecular material may beformed of thin silicon film, for example, besides the polyether urethaneand, in this case, the same functions and characteristics as describedabove can be fulfilled. Furthermore, other material than those mentionedabove may be used insofar as the material can fulfill the same functionsand characteristics as described above.

The electro stimuli-responsive macromolecular material is deformed asshown in FIG. 16. This figure shows a state in which an electric fieldis given (voltage is applied) to a shaft sealing body 250 formed of anelectro stimuli-responsive macromolecular material that is polyurethaneelastomer via fixed electrodes 251 and 252 each opposite locally to theshaft sealing body 250. In the figure, when an electric field is appliedto the fixed electrodes 251 and 252, with the shaft sealing body 250sandwiched between the fixed electrodes 251 and 252, (1) dielectricpolyols or polyols having dipole moment are oriented by the electricfield to change the structure of a macromolecular chain at the oppositeportions of the fixed electrodes 251 and 252 as shown in FIG. 16( a). Atthis time, as shown in FIG. 16( b), (2) the dielectric elastomer isreduced in the width direction by means of the Coulomb effect of theelectric field by the opposite fixed electrodes 251 and 252, therebyexpanding the shaft sealing body 250 in the plane direction. Inaddition, (3) injection and uneven distribution of electric chargeinduce an asymmetric volume change at the electrodes.

Furthermore, in the peripheries of the circumferences of the fixedelectrodes 251 and 252, the electric field is equallyattenuation-distributed in the radial direction (plane direction), witha value at the peripheries of the fixed electrodes 251 and 252 as themaximum value, thereby operating a synthetic deforming stress by thethree functions (1) to (3) to form stress distribution reducing theelectric field homogenously in the plane direction, with the value atthe peripheries of the fixed electrodes 251 and 252 as the maximumvalue. As a result, bend formation is induced.

Incidentally, any of the macromolecular materials may be molded in amaterial shape so as to have characteristics such that the movementsmade when performing or stopping the application of external electrostimuli are reversed. In addition, even in the case of using anymacromolecular material, a fluid leak phenomenon includes so-calledminute leakage that indicates a state in which leakage has induced in ashaft sealed state and, when applying external electro stimuli, thevalue of an electric signal is changed to control the amount ofexpansion or contraction, or the amount of deformation, thereby enablingan optional control of the degree of contact pressure of the shaftsealing body.

Each of the shaft sealing bodies using the electro stimuli-responsivemacromolecular material, electroconductive macromolecular material andionically conductive macromolecular material, of the macromolecularmaterials described above, is retained by a holder capable of retainingit in the upper and lower directions and, by providing the retainingsurfaces of the holder for the shaft sealing body with electrodeselectrically connected to an exterior of the device body, it becomespossible to apply or stop the application of the external electrostimuli from the electrodes to the shaft sealing body.

FIGS. 17 to 19 are schematic views of the shaft sealing devices in whichthe shaft sealing bodies formed respectively of the electrostimuli-responsive macromolecular material, electroconductivemacromolecular material and ionically conductive macromolecular materialare retained by these holders. The shaft sealing device in FIG. 17 has ashaft sealing body 20A formed of the electro stimuli-responsivemacromolecular material and formed in the shape of a disc accompanying aconcentric through-hole 21A and having an appropriate thickness. Theshaft sealing body 20A is provided on the upper and lower surfacesthereof with electrodes 22A and 23A, respectively. The shaft sealingbody 20A is retained from the upper and lower sides by holders 40A and45A that are provided on the surfaces thereof for retaining the shaftsealing body 20A with electrodes 50A and 61A, respectively, and isconfigured to enable applying voltage from the electrodes 50A and 51Athereto via the electrodes 22A and 23A.

When a power source for the shaft sealing device, not shown, has beenturned on to give a potential difference to between the electrodes ofthe holders 40A and 45A, the shaft sealing body 20A retained between theholders 40A and 45A is deformed to expand in the diametrical directionas shown in FIGS. 14 and 17( a), whereas when the electrodes have beendeprived of the potential difference (the power source has been turnedoff), the shaft sealing body is deformed to contract its diameter in thediametrical direction as shown in FIG. 17( b).

The shaft sealing device in FIG. 18 has a shaft sealing body 20B formedof the electroconductive macromolecular material and formed in the shapeof a disc accompanying a concentric through-hole 21B and having anappropriate thickness. In addition, in the case where the shaft sealingbody is formed of the electroconductive macromolecular material, sincethe material has a property of passing a current through itself, it isunnecessary to provide the upper and lower surfaces of the shaft sealingbody with electrodes. The shaft sealing body 20B is retained from theupper and lower sides by holders 40B and 45B that are provided on thesurfaces thereof for retaining the shaft sealing body 20B withelectrodes 50B and 51B, respectively, and voltage is applied from theelectrodes 50B and 51B to the shaft sealing body 20B.

When a potential difference is given to between the electrodes of theholders 40B and 45B, the shaft sealing body 20B retained between theholders 40B and 45B is contracted in the diametrical direction as shownin FIGS. 14 and 18( a), whereas when the electrodes have been deprivedof the potential difference, the shaft sealing body 20B is returned tothe original position while being expanded in the diametrical direction.

The shaft sealing device in FIG. 19 has a shaft sealing body 20C formedof the ionically conductive macromolecular material and formed in theshape of a disc accompanying a concentric through-hole 21C and having anappropriate thickness. The upper and lower surfaces of the shaft sealingbody 20C are provided with electrodes 22C and 23C, respectively. Theshaft sealing body 20C is retained from the upper and lower sides byholders 40C and 45C that are provided on the surfaces thereof forretaining the shaft sealing body 20C with electrodes 50C and 51C,respectively, and voltage is applied from the electrodes 50C and 51C tothe shaft sealing body 20C.

When a potential difference is given to between the electrodes of theholders 40C and 45C, the shaft sealing body 20C retained between theholders 40C and 45C is expanded on the lower surface side and contractedon the upper surface side as shown in FIGS. 14 and 19( a) and, as aresult, entirely deformed to bend, thereby being reduced in shape in thecontracting direction. When the electrodes have been deprived of thepotential difference, the shaft sealing body 20C is returned to theoriginal position while being deformed in the diametrical direction.

In the meantime, FIG. 20 is a schematic view of the shaft sealingdevice, in which retained is a shaft sealing body 20D using an electrostimuli-responsive macromolecular material deforming a section otherthan a section to which external electro stimuli have been applied. Inthe shaft sealing device, the shaft sealing body 20D is formed in theshape of a disc accompanying a concentric through-hole 21D and having anappropriate thickness. The shaft sealing body 20D is provided withelectrodes 22D and 23D sandwiching part of the upper and lower surfacesof the shaft sealing body 20D. The electrodes 22D and 23D areelectrically connected to an exterior of the device body, and it ispossible to perform or stop the application of the external electrostimuli to part of the shaft sealing body 20D. In addition, the shaftsealing body 20D is retained by holders 40D and 45D from the upper andlower directions via the electrodes 22D and 23D.

When a potential difference has been given to between the electrode 22Don the side of the holder 40D and the electrode 23D on the side of theholder 45D, with the electrode 22D as a positive electrode and theelectrode 23D as a negative electrode, the shaft sealing body 20D on theside of the electrode 22D is bend-deformed toward the side of theelectrode 23D to deform part of the shaft sealing body 20D havingemerged as curved, thereby allowing the neighborhood of the outerperiphery of the shaft sealing body 20D to assume a shape contracted inthe diametrical direction. In addition, elimination of the potentialdifference causes the shaft sealing body 20D to be returned to theoriginal position while being deformed in the diametrical direction.

Incidentally, even when using any of the macromolecular materials, byvarying the shape of the shaft sealing body material to be molded, it ispossible to change the movements (NO and NC movements) made whenperforming and stopping the application of the external electro stimulito a movement reverse to the movement shown in the above figure. Also inthis case, the same functions and effects as described above can beobtained. This is applicable to examples to be described later.

Furthermore, in addition to the expansion or contraction, or thedeformation, of the shaft sealing body having the holders retainedthereon, it is possible to expand or contract, or deform, the shaftsealing body having holders and a separator attached thereto. A shaftsealing device provided with a shaft sealing body having a separatorattached thereto will be described.

FIGS. 21 and 22 are schematic views in which a shaft sealing body hasholders and a separator attached thereto. The shaft sealing device inFIG. 21 has a shaft sealing body formed of an electro stimuli-responsivemacromolecular material. The shaft sealing body 30A is formed in theshape of a disc accompanying a concentric through-hole 31A and having anappropriate thickness. The shaft sealing body 30A is provided on theupper and lower surfaces thereof with electrodes 32A and 33A,respectively. The shaft sealing body 30A and a separator 35A areretained by holders 40A and 45A from the upper and lower sides thereof,and the retaining surfaces of the holders are provided with electrodes50A and 51A, respectively. The separator 35A is formed of a flexibleelectroconductive material and brings the electrodes 32A and 50A to aconduction state. The separator 35A has a compliant concentricthrough-hole 36A and fixed to the upper surface of the shaft sealingbody 30A by means of adhesive etc.

In the shaft sealing device, a potential difference has been given tobetween the electrodes of the holders 40A and 45A, the shaft sealingbody 30A retained between the holders 40A and 45A is urged to expand inthe diametrical direction as shown in FIGS. 14 and 21( a) but, at thistime, the compliant separator 35A provided on the upper side preventsthe shaft sealing body 30A from being expanded on the upper side and, asa result, the shaft sealing body 30A is deformed as being curved upwardas the separator 35A as the basis. In addition, the elimination of thepotential difference allows the shaft sealing body to be deformed asreturned to the original position as shown in FIG. 21( b).

The shaft sealing device in FIG. 22 has a shaft sealing body formed ofan electroconductive macromolecular material and, similarly to the caseof the shaft sealing body formed of the electro stimuli-responsivematerial, the shaft sealing body 30B is formed in the shape of a discaccompanying a concentric through-hole 31B and having an appropriatethickness. A separator 35B is fixed to the upper surface of the shaftsealing body 30B by means of adhesion etc. Holders 40B and 45B retainsthe shaft sealing body 30B and separator 35B in the upper and lowerdirections and has the retaining surfaces thereof provided withelectrodes 50B and 51B.

In the shaft sealing device, a potential difference has been given tobetween the electrodes of the holders 40B and 45B, the shaft sealingbody 30B retained between the holders 40B and 45B is urged to contractin the backward direction as shown in FIGS. 14 and 22( a) but, at thistime, the compliant separator 35A provided on the upper side preventsthe shaft sealing body 30B from being contracted on the upper side and,as a result, the shaft sealing body 30B is deformed as being curveddownward as the separator 35B as the basis. In addition, the eliminationof the potential difference allows the shaft sealing body to be returnedto the original position while being expanded.

Incidentally, since the ionically conductive macromolecular material towhich a potential difference is given in a state having holders 40C and45C only attached thereto is deformed as being curved, though attachmentof a separator is not required, a separator may be attached as occasiondemands. In this case, the shaft sealing body is reinforced with theseparator and can function similarly to that provided with no separator.

Furthermore, since it is sufficient that the electro stimuli-responsivemacromolecular material, which has deformed a section thereof other thana section to which external electro stimuli have been applied, isbrought to a state having part of the upper and lower surfaces thereofsandwiched between the electrodes, though attachment of a separator isnot required similarly to the case of the ionically conductivemacromolecular material, a separator may be attached as occasiondemands. As described in the foregoing, the shaft sealing device of thepresent invention may be configured to have different internalstructures using various kinds of macromolecular materials and, thus, anappropriate configuration can be adopted in accordance with the state ofimplementation.

Next, the switching action of the shaft sealing device according to thepresent invention will be described in more detail using a typicalexample selected from the above examples. FIGS. 1 to 3 show one exampleof the shaft sealing device according to the present invention. Theshaft sealing device in this example has a shaft sealing body formed ofan electro stimuli-responsive macromolecular material and has astructure in which the shaft sealing body is retained by a holder only.A device body 10 comprises a housing 11, a shaft portion 15 disposed inthe housing, a shaft sealing body 20 disposed in the shaft sealingportion, and leakage flow passages 13 and 14 formed in the shaft sealingportion 15 for enabling fluid leakage by deformation of the shaftsealing body 20.

The housing 11 is formed in a substantially tubular shape, and the flowpassages within the housing 11 are shaft-sealed with the shaft sealingportion 15. The shaft sealing portion 15 is provided with a seating face16, and the leakage flow passages 13 and 14 are disposed on the oppositesides of the seating face 16 and extend in parallel to each other in thecircumferential direction. After the shaft sealing body 20 is disposedwithin the shaft sealing portion 15, an abutting surface 24 of the shaftsealing body 20 is abutted on the seating face 16 when the shaft sealingbody 20 has been deformed, thereby enabling the formation of a shaftseal. In addition, when the leakage passages 13 and 14 have communicatedwith each other, a fluid can be leaked. Incidentally, though not shown,a flow passage can be configured through connection of an appropriate apipe line, such as a joint or a pipe, to the leakage flow passages 13and 14.

The shaft sealing body 20 accompanies flexible upper and lowerelectrodes 22 and 23 and is configured to enable the value of anelectric signal to be changed when voltage is applied to the electrodes22 and 23. In addition, the shaft sealing body 20 is configured toenable the amount of deformation to be controlled by the change of theelectric signal value and the degree of pressure contact with theseating face 16 to be optionally changed. The shaft sealing body 20assumes a substantially circular outer shape and is provided at thecenter section with a through-hole 21. It goes without saying that theouter shape of the shaft sealing body 20 includes various shapes, suchas quadrangles including a rectangle and a trapezoid, and polygons,besides the annular shape shown in the drawing. The shaft sealing body20 is provided on the outer periphery thereof with the abutting surface24 that can abut on the seating face 16 of the housing 11 and, at thistime, it is possible to establish a shaft sealed state, a minute fluidleakage state in which contact surface pressure is adjustable and afluid leakage state when the abutting surface and the seating face haveseparated from each other to release the shaft sealed state.

In FIGS. 4 and 5, a holder 40 comprises an upper holder 41 and a lowerholder 45 that sandwich the shaft sealing body 20. The upper holder 41has a substantially tubular portion 41 a and a flange portion 41 bdisposed on the lower surface of the tubular portion 41 a. The upperholder 41 is provided with an external electrode 50 extending along theaxial direction from a retaining surface 41 c on the lower surface ofthe flange portion 41 b for retaining the shaft sealing body 20 to partof the inner peripheral surface of the tubular portion 41 a. Theexternal electrode 50 is connected to the exterior of the device body10. When voltage is applied to the external electrode 50, it can beapplied to the upper electrode 22 of the shaft sealing body 20. Thus,the external electrode 50 is patterned on the front surface of the upperholder 41 that is a three-dimensional circuit-molded part.

The lower holder 45 has a substantially columnar portion 45 a and aflange portion 45 b disposed on the lower surface of the columnarportion 45 a. The lower holder 45 is provided with an external electrode51 extending along the axial direction from a retaining surface 45 c forretaining the shaft sealing body 20 to part of the outer peripheralsurface of the columnar portion 45 a. The external electrode 51 isconnected to the exterior of the device body 10. When voltage is appliedto the external electrode 51, it can be applied to the lower electrode23 of the shaft sealing body 20. Thus, similarly to the externalelectrode 50, the external electrode 51 is patterned on the frontsurface of the lower holder 45 with a three-dimensional circuit.

The outside diameter of the flange portions 41 b and 45 b of the upperand lower holders 41 and 45 is made substantially equal to the outsidediameter of the shaft sealing body 20. In addition, the outside diameterof the columnar portion 45 a of the lower holder 45 is made smaller thanthe inside diameter of the inner peripheral surface of the tubularportion 41 a of the upper holder 41 and the inside diameter of thethrough-hole 21 of the shaft sealing body 20 to enable the columnarportion 45 a to be inserted into the inner peripheral part of thetubular portion 41 a.

By inserting a columnar portion 45 d of the lower holder 45 into thethrough-hole 21 and the columnar portion 45 a of the lower holder 45into the tubular portion 41 a of the upper holder 41, the shaft sealingbody 20 is sandwiched between the flange portions 41 b and 45 b. As aresult, the components can be made integral in a state in which theexternal electrodes 50 and 51 on the sides of the flange portions 41 band 45 b have come into contact with the upper and lower electrodes 22and 23 of the shaft sealing body 20, respectively. At this time, sincethe axially extending external electrodes 50 and 51 are disposed atcircumferential positions opposed to each other, they are not broughtinto contact with each other do not induce any short circuit. Inaddition, in the presence of a bump gap, the electrode 51 does notshort-circuit the external electrode 50 patterned on the upper holderflange portion lower side 41 c. When voltage has been applied to theexternal electrodes 50 and 51 and given to the shaft sealing body 20,the shaft sealing body 20 is configured such that it is deformed in thecircumferential direction to enable diameter enlargement.

The holders 41 and 45 can retain the shaft sealing body 20 while locallycoming into pressure contact with it from the upper and lower directionsand, in the presence of the pressure contact portions, it is possible toprevent a fluid from passing through the shaft sealing body and leakingand to perform electrical conduction. In addition, the portions otherthan the pressure contact portions have suitable gaps so as to enablethe shaft sealing body 20 to be expanded or contracted freely.Furthermore, as shown in FIG. 2, the upper side of the inner peripheralsurface of the tubular part 41 a of the upper holder 41 and the upperside of the outer peripheral surface of the columnar part 45 a of thelower holder 45 are provided respectively with grooves 54 and 55 towhich wires not shown are connected. Thus, voltage can be applied fromthe exterior of the device body 10 to the electrodes 50 and 51 via thewires.

With the above configuration, the shaft sealing body 20 is used toenable provision of a structure of an EPAM that is an artificial muscle,and the entire structure has excellent characteristics such that a forcegenerated at the time of the deformation of the shaft sealing body 20can be enlarged and that the entire structure has a light weight, makesa drive structure simple and compact, allows the sound generated duringthe operation to be quiet and can be driven at a low voltage.

The shaft sealing body 20 attached to the holders 41 and 45 is attachedto a attachment body 17 formed in a substantially tubular shape, and theattachment body 17 is attached to the inside of the housing 11. As aresult, the shaft sealing body 20 can be disposed at an appropriateposition within the device body 10. An O-ring 18 is provided between theattachment body 17 and the housing 11 for preventing occurrence ofleakage from between them. In addition, the same effect can be obtainedthrough integral provision of the attachment body 17 and the holder 41.

A power supply circuit 60 is connected to each of the externalelectrodes 50 and 51 so that voltage may be applied to the externalelectrodes 50 and 51 and provided therein with a variable source 61, aswitch 62 and a variable resistor 63 and, when the switch 62 is turnedon to close the circuit, voltages of different polarities are applied tothe electrodes 22 and 23 of the shaft sealing body 20 to performelectric charge. When voltage of negative polarity has been applied tothe external electrode 50 of the upper holder 41, for example, voltageof positive polarity is to be applied to the external electrode 51 ofthe lower holder 45. In addition, these voltages can be controlled withthe variable source 61 or variable resistor 63.

Subsequently, the operation of the above embodiment of the shaft sealingdevice according to the present invention will be described. When theswitch 62 has been turned on as shown in FIG. 3 from the state of FIG.1, voltages of different polarities are applied to the externalelectrode 50 of the upper holder 41 and the external electrode 51 of thelower holder 45, respectively, and to the upper and lower electrodes 22and 23 of the shaft sealing body 20, respectively. As a result, theshaft sealing body 20 is deformed as being expanded in thecircumferential direction and, by this deformation, the abutting surface24 of the shaft sealing body 20 is brought into pressure contact withthe seating face 16 of the device body 10 to shaft-seal the flow passagebetween the leakage flow passages 13 and 14, thereby enabling the fluidto be sealed.

At this time, since adjustment of the variable source 61 or variableresistor 63 controls the amount of voltage (degree of voltage) to beapplied or the applying time of the voltage (transient response) toenable the amount of deformation or deformation response time of theshaft sealing body 20 to be adjusted, the abutment surface 24 can bebrought into contact with the seating face 16 with appropriate suppressstrength, thereby enabling leakage to be effectively prevented and theshaft sealing effect to be heightened. In addition, by increasing thevoltage gradually from the fluid leaked state to deform the shaftsealing body, it is possible to optionally control the state from aminute level of leaked state to a sealed state. Furthermore, bydecreasing the voltage to be applied from the shaft sealed state littleby little, it is possible to control so-called minute leakage thatinduces leakage, with the shaft sealed state maintained. Moreover, bycontinuously decreasing the voltage to be applied, it is possible toadjust by the shaft sealing body 20 the amount of a gap 6 to bedescribed later and, as a result, adjust the flow rate to a prescribedvalue. Thus, the device body 10 can control a minute level of fluidleakage amount in addition to the induction of fluid leakage or thecontrol of the amount of leakage to zero.

On the other hand, when the switch 62 has been turned off as shown inFIG. 1 from the state of FIG. 3, an external discharge circuit, thoughnot shown, discharges an electric charge from the upper and lowerelectrodes 22 and 23 of the shaft sealing body 20 via the externalelectrodes 50 and 51. As a result, the shaft sealing body 20 is broughtto a nonconductive state and deformed as being reduced in diameter inthe circumferential direction to form the concentric gap 8 between theshaft sealing body 20 (abutting surface 24) and the housing 11 (seatingface 16). The fluid kept still sealed is flowed as leaking from the gapδ to enable communication between the flow passages 13 and 14. In thecase, since the amount of the gap δ at the time of turning the switch 62off is peculiar to the device body 10, the amount of the fluid leakedpeculiar to the device body can be produced and utilized as a constantfluid flow rate. As a result, the shaft sealing device can be applied toan electromagnetic valve, for example.

Thus, the device body 10 deforms the shaft sealing body 20 as beingenlarged or reduced in diameter through application of external electrostimuli via the external electrodes 50 and 51. Therefore, the shaftsealing body 20 can seal the fluid in the shaft sealed state in which itis not moved, or flow the fluid while adjusting the amount of leakageafter releasing the shaft sealed state. In addition, when an internalstructure in which the shaft sealing body 20 constitutes a movableportion has been adopted, since there is no need to provide a movingmechanism, such as a screw feeding mechanism, sealing and unsealing ofthe fluid can easily be performed through a reversible switchingoperation. Furthermore, since the shaft sealing body 20 is not twistedat the moving time, it can be prevented from being injured ordeteriorated and maintain an excellent shaft sealing function.

Incidentally, in this example, since the shaft sealing body is formed ofan electro stimuli-responsive macromolecular material, it is deformed asbeing expanded or contracted when voltage has been applied thereto.However, when the shaft sealing body is formed of an electroconductivematerial, it is enlarged or reduced through the expansion or contractionthereof when voltage has been applied thereto. In addition, when theshaft sealing body is formed of an ionically conductive macromolecularmaterial or an electro stimuli-responsive macromolecular materialdeforming a section other than a section to which external electrostimuli have been applied, it is deformed when voltage has been appliedthereto. In addition, since either one of the leakage flow passages 13and 14 may constitutes a primary or secondary flow passage, the fluidcan be leaked or sealed in an optional direction.

Next, another example of the shaft sealing device according to thepresent invention will be described. Incidentally, in the followingexamples, the same portions as in the above example will be given thesame reference numerals and the descriptions thereof will be omitted. Inaddition, also in this example, though the macromolecular material usedas the shaft sealing body includes at least four kinds of macromolecularmaterials, i.e. one being an electro stimuli-responsive macromolecularmaterial, another an electroconductive macromolecular material, anotheran ionically conductive macromolecular material and the remainder anelectro stimuli-responsive macromolecular material deforming a sectionother than a section to which external electro stimuli have beenapplied, the case of using the electro stimuli-responsive macromolecularmaterial will be described in this example for convenience ofexplanation.

In this example, as shown in FIGS. 6 to 8, at least two shaft sealingbodies 80 and 85 are provided within a device body 70, a holder 90capable of retaining the shaft sealing bodies 80 and 85 in the upper andlower directions, respectively, is provided, and retaining surfaces ofthe holder 90 for these shaft sealing bodies are provided withelectrodes electrically connected to the exterior of the device body 70.By performing or stopping application of external electro stimuli fromthe electrodes to deform the shaft sealing bodies 80 and 85, at leastthree fluid flow passages 73, 74 and 75 formed in a substantiallytubular housing 71 for the device body 70 can be switched.

As shown in FIGS. 9 and 10, the holder 90 comprises a first holder 91, asecond holder 92, a third holder 93 and a fourth holder 94 and, betweenadjacent ones of these holders 91, 92, 93 and 94, the two shaft sealingbodies 80 and 85 and a separator 95 intervene, respectively. The firstholder 91 has a substantially tubular portion 91 a and a flange portion91 b on the lower side of the tubular portion 91 a. An electrode 100 isformed to extend along the axial direction from the lower side of theflange portion 91 b retaining the shaft sealing body 80 to part of theinner peripheral surface of the tubular portion 91 a and is connected tothe exterior of the device body 70. As a result, voltage applied fromthe upper side of the tubular portion 91 a to the electrode 100 can beapplied to an upper surface 82 of the shaft sealing body 80.

The second holder 92 has a substantially tubular portion 92 a and aflange portion 92 b on the lower side of the tubular portion 92 a, andan electrode 101 is formed to extend along the axial direction from theupper side of the flange portion 92 b to part of the outer peripheralsurface of the tubular portion 92 a and is connected to the exterior ofthe device body 70. As a result, when voltage has been applied from theelectrode 101, it can be applied to a lower surface 83 of the shaftsealing body 80. The voltage has the opposite polarity to the voltageapplied to the electrode 100.

The third holder 93 has a substantially tubular portion 93 a and aflange portion 93 b on the lower side of the tubular portion 93 a, andan electrode 102 is formed to extend along the axial direction from thelower side of the flange portion 93 b to part of the inner peripheralsurface of the tubular portion 93 a and is connected to the exterior ofthe device body 70. Furthermore, the fourth holder 94 has asubstantially columnar portion 94 a and a flange portion 94 b on thelower side of the columnar portion 94 a, and an electrode 103 is formedto extend along the axial direction from the upper side of the flangeportion 94 b to part of the outer peripheral surface of the columnarportion 94 a and is connected to the exterior of the device body 70. Thevoltage in the electrode 103 of the fourth holder is opposite to that inthe electrode 102 of the third holder.

The electrodes 100, 101, 102 and 103 of the holders 91, 92, 93 and 94can be detached to the exterior from the upper sides of the tubularportions 91 a, 92 a and 93 a and columnar portion 94 a, respectively,and voltage can be applied from an external power circuit to each of theelectrodes. Incidentally, the power source is not shown in this example,but the lead line therefor is only shown.

The outside diameter of the flange portions 91 b, 92 b, 93 b and 94 b issubstantially equal to that of the shaft sealing bodies 80 and 85 andspacer 95. The outside diameter of the spacer 95 may be made smallerappropriately. In addition, it is designed that the relations of theinside diameter of the tubular portion of the first holder 91>theoutside diameter of the tubular portion of the second holder 92, theinside diameter of the tubular portion of the second holder 92>theoutside diameter of the tubular portion of the third holder 93 and theinside diameter of the tubular portion of the third holder 93>theoutside diameter of the columnar portion of the fourth holder 94 havebeen satisfied. The shaft sealing bodies 80 and 85 and the spacer 95have through-holes so as to be attached to, respectively, between thefirst and second holders 91 and 92, between the third and fourth holders93 and 94 and between the second and third holders 92 and 93.

When making these components integral with one another, the tubularportions and columnar portion are inserted into the correspondingtubular portions disposed upward, respectively, with the shaft sealingbody 80 intervening between the first and second holders 91 and 92, theshaft sealing body 85 between the third and fourth holders 93 and 94 andthe spacer 95 between the second and third holders 92 and 93. At thistime, it is configured that the electrodes 100 and 101 of the first andsecond holders 91 and 92 do not come into contact with the electrodes102 and 103 of the third and fourth holders 93 and 94 and, when voltageshave been applied to these electrodes, the voltages of differentpolarities are applied to the upper and lower surfaces of the shaftsealing bodies 80 and 85 to enable the shaft sealing bodies 80 and 85 tobe enlarged in diameter in the circumferential direction, respectively.The shaft sealing bodies 80 and 85 made integral are attached to anattachment body 78 forming a substantially tubular shape in conjunctionwith the holder 90 and spacer 95, and the attachment body 78 is attachedto the inside of the housing 71 via an O-ring 79. In the meanwhile, theattachment body 78 and the holder 91 may be made integral with eachother.

In the state shown in FIG. 6, when the application of voltage to theelectrodes 100 and 101 has been stopped and when voltage has beenapplied to the electrodes 102 and 103, the shaft sealing body 85 isdeformed as being enlarged in diameter by the pressure to bring anabutting surface 89 of the shaft sealing body 85 into contact with aseating face 77, thereby closing a flow passage between the leakage flowpassages 74 and 75. On the other hand, the shaft sealing body 80 betweenthe leakage flow passages 73 and 74 is in non-conductive state tomaintain a diameter-reduced state, thereby inducing a gap δ′ between anabutting surface 84 and a seating face 76 and, therefore, the leakageflow passages 73 and 74 are allowed to communicate via the gap δ′ witheach other to form a leakage flow passage.

Stopping the application of voltage to the electrodes 102 and 103 fromthe state shown in FIG. 6 and applying voltage to the electrodes 100 and101 brings about a state shown in FIG. 8. In the figure, since the shaftsealing body 85 is in a non-conductive state to become in a deformedstate as being reduced in diameter, a gap δ″ is formed between theabutting surface 89 and the seating face 77. On the other hand, theshaft sealing body 80 is in a conductive state to maintain a deformedstate as being enlarged in diameter, thereby bringing the abuttingsurface 84 of the shaft sealing body 80 into pressure contact with theseating face 76. As a result, the flow passage between the leakage flowpassages 73 and 74 is closed, whereas the flow passage between theleakage flow passages 74 and 75 becomes in a state communicating witheach other. In this example, as described above, by providing the pluralshaft sealing bodies 80 and 85 and controlling the application ofvoltage to deform the shaft sealing bodies 80 and 85 and bring theabutting surfaces 84 and 89 into contact with or separate them from theseating faces 76 and 77 provided between the adjacent leakage flowpassages 73, 74 and 75, the leakage flow passages can be switched. Alsoin this case, similarly to the aforementioned example, control of thevoltage to be applied varies the size of the gap δ″ to enable theadjustment of the leakage flow rate and, furthermore, in the case ofadjusting the voltage in the state of bringing the shaft sealing bodyinto pressure contact with seating face, the amount of minute leakagecan be controlled.

In FIG. 11, a holder 110 of a different shape is shown and configured tohave a flange portion 112 provided on the outside diameter side thereofwith plural bored holes 113 and, when having been accommodated within ashaft sealing portion 116 of a housing 115, form a gap a between theshaft sealing portion 116 and the outer periphery of the flange portion112. Incidentally, in this example, the bored holes 113 are disposed inthe circumferential direction of the flange portion 112 at positions onthe outside diameter side thereof from the intermediate positionthereof. The holder 110 can guide a shaft sealing body, not shown, whenhaving been expanded or contracted, or deformed, to make the shape ofthe shaft sealing body stable and enable the flange portion 112 to serveas a guide when the shaft sealing body attached to the holder 110 isinserted into the housing 115.

When the shaft sealing body not shown is attached to the holder 110, theoutside diameter of the shaft sealing body when having been contractedis set to be smaller than the positions of the bored holes 113 and, whenthe shaft sealing body attached to the holder 110 is contracted ordeformed in the diameter-reducing direction, it is possible to secure(increase) the area for passage of a fluid, thereby making it possibleto increase the amount of leakage (flow rate) at the time of shaftsealing leakage. On the other hand, when the shaft sealing body isexpanded or deformed in the diameter-enlarging direction, it can stop upthe bored holes 113 to close the flow passages, thereby making itpossible to seal the fluid with exactitude. The flange portion may beformed with cancellous holes, for example, insofar as it can close theflow passages when the shaft sealing body has been increased in diameteror, when the shaft sealing body has been decreased in diameter, increasethe area for the passage of the fluid. Thus, the mode of the holder doesnot matter. In addition, the above mode of the holder can be utilizedfor any of the aforementioned shaft sealing devices.

FIG. 12 shows an example in which the shaft sealing body is applied to asafety valve 120. In the figure, a device body 121 has a shaft sealingbody 122 capable of being expanded or contracted, or deformed, byperforming or stopping the application of voltage, and the shaft sealingbody 122 is accommodated in a housing 123. The housing 123 is attachedto a pipe 124 so as to allow an internal flow passage thereof tocommunicate with the pipe. In addition, a pressure sensor 125 cantransmit the fluctuation in internal pressure of the pipe 124 as avoltage signal and detect the variation in internal pressure of the pipe124. A switch circuit 126 is disposed between the pressure sensor 125and the device body 121 and configured to enable stopping theapplication of voltage to the device body 121 in accordance with thefluctuation of the pressure detected with the pressure sensor 125.Furthermore, to the switch circuit 126, voltage having a reference valuefor provisionally sealing the shaft sealing body during the course ofthe shaft sealing body 122 reaching a prescribed pressure value in aninitial seal of pressure into the pipe is applied.

The safety valve 120 stops the application of voltage with the switchcircuit 126 when the value of the internal pressure of the pipe 124detected with the pressure sensor 125 has exceeded a prescribed valueand, by the voltage application stopping, the shaft sealing body 122 iscontracted or deformed from the normally expanded or deformed state toform a gap between the housing 123 for the device body 121 and the shaftsealing body 122, thereby enabling the internal pressure of the pipe 124to be lowered through relief of the pressure from the gap. In addition,when the pressure has been returned to the prescribed value or lessafter the pressure relief, the switch circuit 126 is used to apply thevoltage of the pressure sensor 125 to the shaft sealing body 122 tochange the shaft sealing body 122 from the contracted or deformed stateto the expanded or deformed state, thereby enabling sealing pressureleakage.

FIG. 13 shows an example in which the shaft sealing device of thepresent invention is applied to a piston-cylinder drive mechanism 130.In the figure, a device body 131 has four shaft sealing bodies 132, 133,134 and 135 capable of being expanded or contracted, or deformed, in thecircumferential direction accommodated in a housing 136 to enable airflow passages to be switched. The housing 136 is formed therein withleakage flow passages 137, 138, 139, 140 and 141. The leakage flowpassage 137 is provided so as to enable compressed air to be suppliedfrom the exterior to the device body 131, and the leakage flow passages138 and 139 are provided so as to enable the compressed air within thedevice body 131 to be discharged to the exterior. In addition, theleakage flow passages 140 and 141 are connected to a cylinder portion130 a and provided so as to enable supply and discharge the compressedair between the device body 131 and the cylinder portion 130 a.

The shaft sealing bodies 132, 133, 134 and 135 are disposed between theleakage flow passages 138 and 141, between the leakage flow passages 141and 137, between the leakage flow passages 137 and 140 and between theleakage flow passages 140 and 139, respectively, and application ofvoltage to the shaft sealing bodies 132, 133, 134 and 135 is controlledto expand or contract, or deform, these shaft sealing bodies to enable ashaft seal between the adjacent leakage flow passages.

In FIG. 13( a), by making a control so that application of voltage tothe shaft sealing bodies 132 and 134 is stopped to contract or deformthese shaft sealing bodies in the diameter-reducing direction and sothat voltage is applied to the shaft sealing bodies 133 and 135 toexpand or deform these shaft sealing bodies in the diameter-enlargingdirection, the flow passage between the leakage flow passages 137 and140 and the flow passage between the leakage flow passages 141 and 138are allowed to communicate with each other as shown and, at the sametime, the flow passage between the leakage flow passages 139 and 140 andthe flow passage between the leakage flow passages 141 and 137 areclosed, respectively. When compressed air has been supplied from theleakage flow passage 137, with the above state maintained, thecompressed air was sent into the cylinder portion 130 a via the leakageflow passage 140 to move a piston 130 b leftward in the figure. Thismovement of the piston 130 b discharges the compressed air within thecylinder portion 130 a from the leakage flow passage 138 via the leakageflow passage 141.

On the other hand, in FIG. 13( b), by making a control so that voltageis applied to the shaft sealing bodies 132 and 134 to expand or deformthese shaft sealing bodies in the diameter-enlarging direction and sothat application of voltage to the shaft sealing bodies 133 and 135 isstopped to contract or deform these shaft sealing bodies in thediameter-reducing direction, the flow passage between the leakage flowpassages 137 and 141 and the flow passage between the leakage flowpassages 140 and 139 are allowed to communicate with each other as shownand, at the same time, the flow passage between the leakage flowpassages 141 and 138 and the flow passage between the leakage flowpassages 137 and 140 are closed, respectively. When compressed air hasbeen supplied from the leakage flow passage 137, with the above statemaintained, the compressed air was sent into the cylinder portion 130 avia the leakage flow passage 141 to move a piston 130 b rightward in thefigure. This movement of the piston 130 b discharges the compressed airwithin the cylinder portion 130 a from the leakage flow passage 139 viathe leakage flow passage 140. Thus, in the piston-cylinder drivemechanism 130, it is possible to switch the flow passages through thecontrol of the application of voltage to each of the shaft sealingbodies 132, 133, 134 and 135 and enable the piston 130 b to reciprocatethrough the supply of the compressed air from one of the leakage flowpassages 137.

Though the cases of providing the shaft sealing device of the presentinvention with the safety valve 120 and the piston-cylinder drivemechanism 130 have been described above, these are absolutely mereexamples. The shaft sealing device of the present invention canshaft-seal the primary and secondary sides of a fluid flow passage andrelease the shaft seal to induce a prescribed leakage amount, and may beapplied to various apparatus and mechanisms insofar as minute leakagecan be controlled.

Though not shown, the shaft sealing device of the present invention maybe configured have the shaft sealing portion formed like a room toconstitute a shaft sealing chamber in which a fluid can be accommodatedbesides the configuration thereof as part of a flow passage. Inaddition, the device body may be formed of a material resistant to adrug solution or provided as an internal structure, thereby enablingsupply of the drug solution while sealing the drug solution orcontrolling the flow rate of the drug solution. As a result, it ispossible to provide the shaft sealing device as part of a liquid crystalfabricating plant or a semiconductor precision plant. In this case, thematerial for a pipe connected to an inlet or outlet side of the devicecan be selected freely and, in accordance with a fluid to be used, canbe changed appropriately.

Next, a valve structure using the shaft sealing device will bedescribed. In the shaft sealing device in this case, an annular shaftsealing body is inserted into a device body via a holder, the shaftsealing body has a base fixed to the holder or device body and anopposite free end and, when external electro stimuli have been appliedto the shaft sealing body, the shaft sealing body is expanded orcontracted in the shape of a substantially perfect circle, with the freeend as a shaft sealing portion, thereby obtaining a shaft sealed stateor a fluid leaked state.

In the valve structure using the shaft sealing device, the device bodyis formed therein with plural flow passages communicating with theexterior, and the shaft sealing portion that are the free end of theshaft sealing body is disposed between the flow passages to bring theshaft sealing portion to a shaft sealed state or liquid leaked state,thereby enabling switching the flow passages.

In FIG. 23, macromolecular materials of which the shaft sealing body isformed and which are used in the valve structure are shown. Themacromolecular materials used in the valve structure can be expanded ordeformed through external electro stimuli similarly in the case of theaforementioned shaft sealing device and includes at least three kinds ofmaterials, i.e. one being an electro stimuli-responsive macromolecularmaterial, another an electroconductive macromolecular material and theremainder an ionically conductive macromolecular material. Thecharacteristics of these macromolecular materials are the same as thoseof the aforementioned macromolecular materials. Though the descriptionof an electro stimuli-responsive macromolecular material having asection, other than a section to which external electro stimuli havebeen applied, deformed is omitted, this macromolecular material havingan appropriate configuration can be utilized in the valve structureusing the shaft sealing device, similarly to the three kinds of themacromolecular materials described herein below. The characteristics ofthe macromolecular material are the same as those of the aforementionedmacromolecular material.

In the shaft sealing body using the electro stimuli-responsivemacromolecular material or ionically conductive macromolecular materialas the macromolecular material, a plate-shaped base is provided on thefront and back surfaces thereof with electrodes, respectively and, inthe case of using an electroconductive macromolecular material as themacromolecular material, there is no need to provide the front and backsurfaces of the plate-like base with electrodes, but the plate-like baseis molded into an annular shape. In addition, the shaft sealing body, ifformed of an electro stimuli-responsive macromolecular material or anionically conductive material, is provided on hollow cylindrical innerand outer peripheral surfaces thereof integrally with electrodes,respectively. FIGS. 24 to 26 are schematic views showing a plate-shapedbase material of a shaft sealing body formed into an annular shape.

The valve structure in FIG. 24 has a shaft sealing body 160A which isformed of an electro stimuli-responsive macromolecular material andwhich has a plate-like base material 161A having electrodes 162A and163A patterned on the outer and inner peripheries thereof. The basematerial 161A is formed in a concentric hollow cylindrical shape. Aseparator 168A formed of a material having compliant characteristics,such as a resin, is attached integrally to the outer periphery of theshaft sealing body 160A to allow the separator 168A and the shaftsealing body 160A to be operated integrally.

A holder 170A retains the shaft sealing body 160A from the innerperiphery thereof so that voltage may be applied from the exterior tothe electrodes 162A and 163A of the shaft sealing body 160A viacommunication holes 171A and 172A formed in the holder 170A andthrough-holes 164A and 165A formed in the shaft sealing body 160A. Inaddition, the shaft sealing body 160A has the through-holes 164A and165A fixed to the communication holes 171A and 172A of the holder 170Ato form a base 166A and has a free end 167A, opposite to the base 166A,enabled to expansion-deform in the shape of a substantially perfectcircle relative to the holder 170A.

In the valve structure, when a power source not shown has been turned onand a potential difference has been given to between the electrodes 162Aand 163A on the outer and inner peripheries of the tubular shaft sealingbody 160A, the shaft sealing body 160A is deformed in a direction ofbeing expanded in the axial direction. At this time, since the shaftsealing body 160A has its surface on the side of the separator 168Amaintained, the shape of the inner periphery on the side opposite to theside of the separator 168A is more expanded. Therefore, as shown inFIGS. 23 and 24( a), the shaft sealing body 160A has the free end 167A,except for the base 166A, is deformed as being enlarged in diameterrelative to the holder 170A maintaining a reference cylindrical shape.In addition, when the potential difference has been eliminated, as shownin FIG. 24( b), the free end 167A of the shaft sealing body is returnedto the original position as being deformed to reduce its diameter alongthe holder 170A.

Furthermore, the valve structure in FIGS. 25 and 26 has a shaft sealingbody 160B formed of an electroconductive macromolecular material and, inthis case, there is no need to provide the shaft sealing body withelectrodes, and a base material 161B is formed into a concentric hollowcylindrical shape. A separator 168B is formed of a resin similarly tothe case of FIG. 24. The separator 168B adheres integrally to the outerperiphery of the shaft sealing body 160B in FIG. 25 and to the innerperiphery of the shaft sealing body 160B in FIG. 26.

A holder 170B retains the shaft sealing body 160B from the innerperiphery thereof, and it is configured that voltage can be applied fromthe exterior to the outer and inner peripheral surfaces 162B and 163B ofthe shaft sealing body 160B via communication holes 171B and 172B formedin the holder 170B and through-holes 164B and 165B formed in the shaftsealing body 160B. In addition, the shaft sealing body 160B has thethrough-holes 164B and 165B fixed to the communication holes 171B and172B of the holder 170B to form a base 166B, and a free end 167Bopposite to the base 166B can be expanded or contracted, or deformed, inthe shape of a substantially perfect circle relative to the holder 170B.

In the valve structure of FIG. 25, when a potential difference has beengive to between the outer and inner peripheral surfaces 162B and 163B ofthe shaft sealing body 160B, the shaft sealing body 160 is urged toexpand in the axial direction. At this time, since the shape of theshaft sealing body 160B on the side of the separator 168B is maintained,the inner periphery of the shaft sealing device on the side opposite tothe side of the separator 168B is more expanded. As shown in FIGS. 23and 25( b), therefore, the shaft sealing body 160B has the free end167B, except for the base 166, enlarged in diameter relative to andalong the holder 170A assuming the reference cylindrical shape. When thepotential difference has been eliminated, as shown in FIG. 25( a), thefree end 167B is returned to the original position as being contracted.

On the other hand, in the valve structure of FIG. 26, when a potentialdifference has been give to between the outer and inner peripheralsurfaces 162B and 163B of the shaft sealing body 160B, the shaft sealingbody 160B is urged to contract in the axial direction. At this time,since the shape of the shaft sealing body 160B on the side of theseparator 168B is maintained, the outer periphery of the shaft sealingdevice on the side opposite to the side of the separator 168B is morecontracted. As shown in FIGS. 23 and 26( a), therefore, the shaftsealing body 160B has the free end 167B, except for the base 166B,enlarged in diameter relative to the holder 170B. When the potentialdifference has been eliminated, as shown in FIG. 26( b), the free end167B is returned to the original position as being expanded relative toand along the holder 170B.

The valve structure in FIG. 27 has a shaft sealing body 160C formed ofan ionically conductive macromolecular material and, similarly to thecase of the electro stimuli-responsive macromolecular material, aplate-like base material 161C has electrodes 162C and 163C patterned onthe outer and inner peripheries thereof and is formed in a concentrichollow cylindrical shape. Similarly to the shaft sealing device of FIG.19, there is no need to attach a separator to the shaft sealing body160C. However, the separator may be attached as occasion demands.

A holder 170C retains the shaft sealing body 160C from the innerperiphery thereof, and it is configured that voltage can be applied fromthe exterior to the electrodes 162C and 163C via communication holes171C and 172C formed in the holder 170C and through-holes 164C and 165Cformed in the shaft sealing body 160C. In addition, the shaft sealingbody 160C has the through-holes 164C and 165C fixed to the communicationholes 171C and 172C of the holder 170C to form a base 166C, and a freeend 167C opposite to the base 166C can be expanded or contracted, ordeformed, in the shape of a substantially perfect circle relative to theholder 170C.

In the valve structure of FIG. 27, when a potential difference has beengiven to between the electrodes 162C and 163C on the outer and innerperipheries of the shaft sealing body 160C, since the shaft sealing body160C has the inner peripheral surface expanded and the outer peripheralsurface contracted, the free end 167, except for the base 166C, assumesa shape having the distal end thereof more expanded as shown in FIG. 27(a). In addition, when the potential difference has been eliminated, asshown in FIG. 27( b), the free end 167C is returned to the originalposition as extending along the holder 170C.

Next, the switching operation of the flow passages in the valvestructure will be described using a typical example selected from theabove examples. FIGS. 28 to 30 show one example of the valve structureusing the shaft sealing device. As shown in FIGS. 30( b) and 30(c), ashaft sealing body 160 has front and back surfaces 161 a and 161 b of abase material 161 provided with electrodes 162 and 163, respectively,and has the base material 161 molded into an annular shape as shown inFIG. 30( a). FIG. 30( b) is a development view having the shaft sealingbody 160 developed, with line ab-a′b′ in FIG. 30( a) as a cutting-planeline, and a hatched portion in the figure denotes the electrode 162. Inaddition, FIG. 30( c) is a development view showing the backside of FIG.30( a), and a hatched portion in the figure denotes the electrode 163.

The electrodes 162 and 163 have belt-like electrodes 162 a and 163 a,respectively, each having a width one half the width of the shaftsealing body 160 in the axial direction and, when the shaft sealing body160 is molded into a perfect circle, the belt-like electrodes 162 a and163 a are formed on the front and back surfaces 161 a and 162 adescribing circumferences, respectively. Extraction electrodes 162 b and163 b drawn from and connected to the belt-like electrodes 162 a and 163a, respectively, are provided with through-holes 164 and 165 opposed toeach other, whereby voltage can be applied to the entire electrodes fromthe through-holes 164 and 165 via the extraction electrodes 162 b and163 b. Since the configuration is such that voltage is applied to theelectrodes 162 and 163 on the front and back surfaces via thethrough-holes 164 and 165 as described above, the electrodes 162 and 163are not short-circuited, and it is possible to apply voltages ofopposite polarities to the front and back surfaces 161 a and 161 b ofthe shaft sealing body 160.

A holder 170 comprises a substantially circular portion 170 a, adiameter-increasing portion 170 b slightly larger in diameter than thecylindrical portion 170 a and a lid portion 170 c larger in diameterthan the diameter-increasing portion 170 b. The cylindrical portion 170a has an outside diameter not shown but made slightly smaller than theinside diameter, not shown, of the shaft sealing body 160 and has theouter periphery thereof to which the shaft sealing body 160 can beattached. In addition, the diameter-increasing portion 170 b has anoutside diameter not shown but made substantially equal or slightlysmaller than the inside diameter, not shown, of a device body 150 andcan be inserted into the inside diameter of the device body 150. The lidportion 170 c has an outside diameter capable of covering an opening end152 of the device body 150. Furthermore, the holder 170 is formed withcommunication holes 171 and 172 at positions corresponding to those ofthe through-holes 164 and 165 of the shaft sealing body 160 and, via thecommunication holes 171 and 172, wires can be connected from the powersupply circuit 60 to the electrodes 162 and 163, respectively. The powersupply circuit 60 has the power source 61 and switch 62 and, when theswitch 62 has been turned on, the circuit is closed to enable voltage tobe applied to the electrodes 162 and 163. The circuit 60 may be providedtherein with a variable resistor not shown to enable the voltage to beadjusted. In addition, the polarities of the power source 61 are notlimited to those shown in FIGS. 28 and 29, but may be vise versa.

The shaft sealing body 160 is attached to the position of thediameter-increasing portion 170 b of the holder 170 while subjecting thethrough-holes 164 and 165 and the communication holes 171 and 172 toalignment with each other, respectively, thereby enabling the shaftsealing body 160 to the holder 170 in an appropriately positioned state,and it is possible to connect the power supply circuit 167 from theinside of the holder 170 to the electrodes 162 and 163 via thecommunication holes 171 and 172. This connection can be attained byconnecting the electrode 163 to the extraction electrode 163 b on theinner peripheral side via the communication hole 172, whereas theelectrode 162 is connected to the extraction electrode 162 b on theouter peripheral side in a state in which the communication hole 171 andthrough hole 164 are allowed to communicate with each other.

After the connection of the power supply circuit 60 to the electrodes162 and 163, an appropriate fixing material is sealed in thethrough-holes 164 and 165 and communication holes 171 and 172 to fix abase 166 of the shaft sealing body 160 to the holder 170. A free end 167opposite to the base 166 can be deformed as being enlarged or reduced indiameter in the shape of a substantially perfect circle relative to theholder 170. In addition, the sealed-in fixing material seals thethrough-holes and communication holes, thereby preventing a fluid fromentering the holder 170. Furthermore, the inside of the holder 170 maybe filled with a potting material shown by two-dot chain lines.

The shaft sealing body 160 is inserted via the holder 170 into thedevice body 150 and, at the time the insertion, the diameter-increasingportion 170 b is inserted until the lid portion 170 c of the holder 170is abutted on the opening end 152 of the device body, thereby obtainingthe appropriate position enabling the free end 167 to be abutted on aseating face that constitutes a valve seal. In addition, since theopening end 152 is formed with an annular groove 152 a to which anO-ring 154 is attached, after the holder 170 and device body 150 aremade integral with each other, the O-ring 154 seals between the devicebody 150 and the holder 170 to prevent a fluid from leaking between thetwo.

Furthermore, the cylindrical device body 150 is formed in thecircumferential face direction with plural flow passages 155 and 156communicating with the exterior, and the seating face 153 is providedbetween the flow passages 155 and 156. In the valve structure, whenexternal electro stimuli have applied to the shaft sealing body 160, thefree end 167 is expanded or contracted, or deformed, in the shape of asubstantially perfect circle. By bringing the free end 167 that forms ashaft sealing portion into contact with or separating the same from theseating face 153 to obtain a shaft sealed state or fluid leakage state,thereby causing the flow passages 155 and 156 to be switchable.

When the switch 62 has been turned on from the state of FIG. 28,voltages of opposite polarities are applied to the electrodes 162 and163. Since the shaft sealing body 160 is formed in a substantiallycylindrical shape, with the opposite surfaces thereof provided with theelectrodes 162 and 163, and has the base 166 fixed to the holder 170 andthe free end 167, the shaft sealing body 160 is urged to deform as beingenlarged in diameter in proportion as it goes to its distal end at thetime of the application of voltage. As a result, the shaft sealing body160 has the free end 167 enlarged in diameter in the circumferentialdirection more than the base 166, i.e. assumes a shape widening towardthe end (a trumpet shape). The shape in the diameter-enlarged state hasa cross section in the direction orthogonal to the axis becomes a shapeof a substantially perfect circle. The free end 167 of the shape of thesubstantially perfect circle is brought into circumferential pressurecontact with the perfectly circular seating face 153 when higher voltagehas been applied thereto to close between the passages 155 and 156,thereby enabling the shaft sealed state to be obtained. Furthermore, bycontrolling the applied voltage to be lowered little by little from theshaft sealed state, the minute leakage amount can be adjusted to theprescribed flow rate to enable the shaft sealing body 160 to be operatedas a valving element.

On the other hand, when the switch has been turned off from the state ofFIG. 29, the shaft sealing body 160 is in a nonconductive state and, asshown in FIG. 28, the free end 167 is returned to the original state inwhich it is deformed as being reduced in diameter and the entire shaftsealing body 160 assumes the substantially tubular shape. Thisdeformation forms a gap between the shaft sealing body 160 and thedevice body 150 to allow the flow passages 155 and 156 to communicatewith each other to enable the fluid to flow.

At this time, in order for the free end 167 to establish the shaftsealed state with exactitude, it is necessary process the seating face153 with high precision to enhance the surface roughness and thedimensional precision including circularity and select a materialsuitable for sealing relative to the shaft sealing body 160 to form thedevice body 150 so as not to induce leakage. In this case, the devicebody is fabricated so that a gap between the device body 150 and theshaft sealing body 160 when the shaft sealing body 160 has been reducedin diameter may be around 0.5 mm and, as a result, a fluid can flow atthe time of the diameter reduction and minute leakage induced when theshaft sealing body 160 has been enlarged or contracted in diameter canbe controlled with high precision.

Incidentally, the shaft sealing body formed of the ionically conductivemacromolecular material has been described in the valve structure usingthe shaft sealing device in this example. However, it goes withoutsaying that the shaft sealing body may be formed of an electrostimuli-responsive macromolecular material, an electroconductivemacromolecular material, an electro stimuli-responsive macromolecularmaterial having a section, other than a section to which externalelectro stimuli have been applied, deformed, or other macromolecularmaterial. In this case, a valve structure is adopted to meet each of themacromolecular materials to be used. When the shaft sealing body isformed of an electroconductive macromolecular material, for example,there is no need to provide the shaft sealing body with electrodes. Inaddition, when the shaft sealing body is formed of an electrostimuli-responsive macromolecular material or an electroconductivemacromolecular material, a flexible separator 169 is attached to themacromolecular material on the side of the outer or inner periphery ofthe shaft sealing body 160.

FIGS. 31 to 33 show an example in which the valve structure using theshaft sealing device is applied to a multiway valve. In the valvestructure, a shaft sealing body 190 is formed of an ionically conductivemacromolecular material and has a substantially central neighborhoodthereof serving as a base 196 fixed to a cylindrical portion 201 of aholder 200 and opposite ends thereof serving as free ends 197 and 198.As shown in FIG. 33, the shaft sealing body 190 has front and backsurfaces 191 a and 191 b of the axial opposite ends provided withbelt-like electrodes 192 a ₁ and 192 a ₂ and belt-like electrodes 193 a₁ and 193 a ₂, respectively, and extraction electrodes 192 b ₁, 192 b ₂,193 b ₁ and 193 b ₂ extend from the belt-like electrodes 192 a ₁, 192 a₂, 193 a ₁ and 193 a ₂ to the axial central neighborhood, therebyconstituting electrodes 192 and 193. At this time, electrodes of thesame polarity are disposed on different ends of the front and backsurfaces 191 a and 191 b of the shaft sealing body 190 via onethrough-hole, and voltages of the same polarity can be applied from onethrough-hole to the electrode on the front surface 191 a of one end andto the electrode on the back surface 191 b of the other end.

For example, since a through-hole 194 is connected to the extractionelectrodes 192 b ₁ and 192 b ₂ and since the extraction electrodes 192 b₁ and 192 b ₂ are connected to belt-like electrodes 192 a ₁ and 192 a ₂,it is possible to apply voltage from the through-hole 194 to theelectrodes 192 and 192 on the front and back surfaces at the same time.On the other hand, since electrodes are similarly configured withrespect to a through-hole 195, voltage can simultaneously be appliedfrom the through-hole 195 to the electrodes 193 and 193 on the front andback surfaces. Furthermore, in this example, since the polarities of apower supply circuit not shown can be switched, voltages of oppositepolarities can be applied to the electrodes 192 and 193, respectively.

A device body 180 has three flow passages 185, 186 and 187 formedtherein in a circumferential direction and two inner cylindrical annularportions (seating faces) 183 and 184 formed on the inner peripherythereof and sandwiched between the adjacent two of the three flowpassages 185, 186 and 187. When the shaft sealing body 190 has beeninserted into the device body 180 via the holder 200, the two free ends197 and 198 are disposed at the positions of the two inner cylindricalannular portions 183 and 184 and, when voltage has been applied toexpand or contract the free ends 197 and 198, the free ends 197 and 198are brought into contact with or separated from the inner cylindricalannular portions 183 and 184, as shaft sealing portions, therebyenabling switching the flow passages 185, 186 and 187.

FIG. 31 shows a state, in which voltages have been applied to the frontand back surfaces of the free end 197 so that the front side of the freeend 197 may be contracted relative to the shaft sealing body 190 and theback side thereof may simultaneously be expanded relative to the same.At this time, the free end 197 is brought into pressure contact with theinner cylindrical annular portion 183 while being enlarged in diameterand maintaining the shape of a substantially perfect circle, therebyobtaining a shaft-sealed state. On the other hand, since voltage of anopposite polarity to that applied to the free end 197 has been appliedto the front and back surfaces of the free end 198, the free end 198 isurged to have the front side expanded and the back side contracted. As aresult, the free end 198 is contracted in the inside diameter directionand brought to a state in which the free end is separated from the innercylindrical annular portion 184. Consequently, a space between the flowpassages 185 and 186 is shaft-sealed with a circumferential seal by thefree end 197, whereas a gap is formed between the flow passages 186 and187 communicating with each other to enable a fluid to flow from theflow passage 186 to the flow passage 187 as shown in the figure.

On the other hand, in FIG. 32, the polarities of voltages from the powersupply circuit are switched to apply voltage of a polarity, whichenables the front surface of the free end 197 to be expanded and theback surface thereof to be contracted, to the free end and apply voltageof a polarity, which enables the front surface of the free end 198 to becontracted and the back surface thereof to be expanded, to the free end.In this case, the free end 197 is contracted in the inside diameterdirection to separate from the inner cylindrical annular portion,whereas the free end 198 is urged to enlarge its diameter whilemaintaining the shape of a substantially perfect circle. Consequently, agap is formed between the flow passages 185 and 186 and, at the sametime, a space between the flow passages 186 and 187 is shaft-sealed toenable a fluid to flow from the flow passage 186 to the flow passage185. With this valve structure, since it is possible to seal the innercylindrical annular portions 183 and 184 of the cylindrical device body180 and switch the fluid from the flow passage 186 to the flow passage185 or 187, it is possible to provide an on-off valve having a simpleand compact structure and capable of being fabricated at low cost.

Incidentally, when the opposite ends of the shaft sealing body are madefree, by forming the shaft sealing body of the ionically conductivemacromolecular material or electro stimuli-responsive macromolecularmaterial having a section, other than a section to which externalelectro stimuli have been applied, deformed, as is done in thisembodiment, the application of voltage enables the opposite side freeends to be expanded and contracted, respectively, even in the case wherethe front and back surfaces of the base material are provided withelectrodes of opposite polarities at the opposite free ends. This isbecause the ionically conductive macromolecular material can reverse itsdeformation (expansion or contraction) direction by changing thepolarity of the voltage to be applied. When using an electrostimuli-responsive macromolecular material or electroconductivemacromolecular material and making the opposite ends free, however, thedeformation direction or expansion or contraction direction of themacromolecular materials at the time of performing or stopping theapplication voltage is decided irrespective of a difference in polarity,it is impossible that the opposite free ends of a single base materialare deformed (expanded or contracted) in different directions.Therefore, when using each of these macromolecular materials and makingthe opposite ends free, two base materials of the same material areattached to the inner or outer peripheral surface of the macromolecularmaterial to obtain an integral body, an electrode is disposed on each ofthe base materials and, with this state maintained, the entirety isattached to the holder.

Subsequently, FIGS. 34 and 35 show another example in which the valvestructure using the shaft sealing device is applied to a multiway valve.In this example, the valve structure has two shaft sealing devices ofFIG. 31 continuously disposed in the axial direction, and the free endof each shaft sealing body is used as a shaft sealing portion that isbrought to a shaft-sealed state or fluid leakage state, thereby making alarge number of fluid passages switchable.

In the valve structure, a device body 210 is formed with five flowpassages 216, 217, 218, 219 and 220 in the circumferential direction andfour inner cylindrical annular portions (seating faces) 212, 213, 214and 215 each sandwiched between adjacent two of the flow passages 216,217, 218, 219 and 220. The holders 200 each having the shaft sealingbody 190 attached thereto are inserted from two opening ends 211 a and211 b into the device body 210, respectively, to bring the free ends 197and 198 of the shaft sealing bodies 190 and 190 into contact with orseparate them from the inner cylindrical annular portions 212, 213, 214and 215, thereby making it possible to switch the five flow passages. Inaddition, different power supply circuits are connected to the shaftsealing bodies 190 to enable the shaft sealing bodies 190 to be operatedindividually.

In FIG. 34, voltages of polarities capable of contracting the free end197 of the upper shaft sealing body 190 in diameter and, at the sametime, enlarging the free end 198 in diameter are applied from the powersupply circuits, and voltages of polarities capable of contracting thefree end 197 of the lower shaft sealing body 190 in diameter and, at thesame time, enlarging the free end 198 are applied from the power supplycircuits. In this case, the flow passages 218 and 219 are allowed tocommunicate with each other, the flow passages 216 and 217 are alsoallowed to communicate with each other, and spaces between other flowpassages are brought to a shaft-sealed state. As a result, a fluid canbe flowed from the flow passage 218 to the flow passage 219 and from theflow passage 217 to the flow passage 216.

On the other hand, in FIG. 35, voltages of polarities capable ofenlarging the free end 197 of the upper shaft sealing body 190 indiameter and, at the same time, contracting the free end 198 in diameterare applied from the power supply circuits, and voltages of polaritiescapable of enlarging the free end 197 of the lower shaft sealing body190 in diameter and, at the same time, contracting the free end 198 areapplied from the power supply circuits. In this case, the flow passages218 and 217 are allowed to communicate with each other, the flowpassages 219 and 220 are also allowed to communicate with each other,and spaces between other flow passages are brought to a shaft-sealedstate. As a result, a fluid can be flowed from the flow passage 218 tothe flow passage 217 and from the flow passage 219 to the flow passage220.

In the valve structure using the shaft sealing device, therefore, byconnecting an air supply opening and an exhaust opening of an airpressure operable actuator not shown to the flow passages 217 and 219,for example, when compressed air has been supplied from the flow passage218 in the state of FIG. 34, it is possible to send the compressed airto a first air chamber of a cylinder not shown via the flow passage 219and, at the same time, exhaust the compressed air from a second airchamber disposed across a piston within the cylinder via the flowpassage 217 out of the flow passage 216.

In addition, when compressed air has been supplied from the flow passage218, with the flow passages switched to the state of FIG. 35, it ispossible to supply the compressed air to the second air chamber via theflow passage 217 and, at the same time, exhaust the compressed air fromthe first air chamber via the flow passage 219 out of the flow passage220.

Thus, the valve structure using the shaft sealing device is used as anelectromagnetic changeover valve, for example, to enable controlling theoperation of the actuator and, as described above, it is possible to usethe free end of the shaft sealing body as the shaft sealing portion thatis brought into contact with or separated from at least two innercylindrical annular portions (seating faces), thereby making it possibleto switch the flow passages. In addition, a multiway valve can beprovided through disposing two or more shaft sealing bodies within thedevice body.

Incidentally, in this example, since the flow passages 216, 217, 218,219 and 220 are formed in different circumferential directions of thedevice body and, as a consequence, this example can be applied to allkinds of multiway valves. In addition, in each of the examples describedabove, the base of the shaft sealing body is attached to the holder.However, the shaft sealing body can be fixed to the device body and,also in this case, the shaft-sealed state or fluid leakage state can beobtained in the same manner as described above.

Example 1

Next, the practicability of each of the shaft sealing device and thevalve structure according to the present invention was examined throughthe simulation of the deformation state of the shaft sealing body of thepresent invention by the CAE analysis. Since it was difficult to confirmthe state of deformation of an actual shaft sealing body when havingbeen expanded or contracted, an analysis of the state of deformation ofa workpiece was made by the CAE analysis. The results of the analysiswere substituted for the deformations of the actual shaft sealing bodywhen having been expanded or contracted. The CAE analysis methodincluded the steps of giving a temperature difference to between theinner and outer peripheries of the workpiece and confirming the state ofdeformations when having been expanded or contracted due to thetemperature difference.

The workpieces used in the analysis are shown in FIGS. 36 and 37. Asshown in FIG. 36, the workpiece A was a single layer of cylinder havingdimensions of 7 mm in outside diameter, 5 mm in inside diameter and 10mm in height at 24.85° C. (normal temperature) and having one endthereof constrained and the other end thereof made free, expansible andcontractible. The conditions of constraint included the steps ofdividing the height of 10 mm into two sections H₁ and H₂, constrainingboth the inner and outer peripheries of the section H₁ and making boththe inner and outer peripheries of the section H₂ free. The workpiece Awas used to simulate the movements of the shaft sealing body 160 formedof an ionically conductive macromolecular material as shown in FIG. 28and make analyses through substitution of the section H₁ for theneighborhood of the base 166 of the shaft sealing body 160 and of thesection H₂ for the neighborhood of the free end 167.

On the other hand, the workpiece B shown in FIG. 37 had the samedimensions as the workpiece A, was axially divided into two members X7mm in outside diameter (6 mm in inside diameter) and Y 6 mm in outsidediameter (5 mm in inside diameter) and integrally combining the twomembers X and Y together. At that time, a heat-insulating layer 0.1 mmin thickness not shown was allowed to intervene between the members Xand Y in order to prevent heat transfer between the respective members.The conditions of constraint of the workpiece B included the steps ofdividing the height of 10 mm into two sections H₃ and H₄, constrainingboth the inner and outer peripheries of the section H₃ and making boththe inner and outer peripheries of the section H₄ free, similarly to thecase of the workpiece A. The workpiece B was used to simulate themovements of the shaft sealing body 160 of FIG. 28 formed of an electrostimuli-responsive macromolecular material or an electroconductivemacromolecular material in the case of using the separator 169, allowthe shaft sealing body 160 to serve as the member Y and the separator169 to serve as the member X and make analyses through the substitutionof the section H₃ for the neighborhood of the base 166 and the sectionH₄ for the neighborhood of the free end 167.

The material for each workpiece might have an appropriate linearcoefficient of expansion and, when it was TFE (tetrafluoroethylene), forexample, the linear coefficient of expansion thereof was 79.0×10⁻⁵/° C.at 20° C., 20.0×10⁻⁵/° C. at 0° C., 16.0×10⁻⁵/° C. at 30° C.,12.4×10⁻⁵/° C. at 50° C. and 13.5×10⁻⁵/° C. at −50° C., for example. Asthe linear coefficient of expansion thereof at a set temperature havingno temperature value, the value obtained by the regression calculationwas adopted. In addition, the Poisson ratio of each workpiece before andafter the deformation thereof was set to be 0.46.

The temperatures set for sections during heat transfer to the workpieceA are shown in Table 1. At that time, the inner periphery of theworkpiece A was expressed as the inner avoiding surface on the innerperiphery and the outer periphery thereof as the outer avoiding surfaceon the outer periphery, and the combinations of the temperatures onthese surfaces were as shown in the table.

TABLE 1 Inner avoiding surface Outer avoiding surface No. on innerperiphery on outer periphery Set 1 0 0 Temperature 2 −20 +20 (° C.) 3−40 +40 4 +20 −20 5 +40 −40

The temperatures set for sections during heat transfer to the workpieceB are shown in Table 2. The entire members X and Y of the workpiece Bwere give temperatures, respectively. This was because the state ofdeformations made by giving relative temperature differences to theinner and outer peripheries of the workpiece B was substituted for thestate of deformations of the shaft sealing body and the separator in theshaft sealing body having the separator attached thereto.

TABLE 2 No. Entire member X Entire member Y Set 6 0 0 temperature 7 −20+20 (° C.) 8 −40 +40 9 +20 −20 10 +40 −40

The state of each of the workpieces A and B was, as shown in theschematic view of FIG. 38 when the inner periphery was set at lowtemperatures (minus temperatures) and the outer periphery at hightemperatures (plus temperatures), such that a distal end (free end) 230of each workpiece had a diameter shape contracted more in proportion asit went toward the distal end side while maintaining a shape of asubstantially perfect circle. At that time, that tendency was furtherstrengthened in the case where the temperature difference between theinner and outer peripheries became larger.

For example, the maximum amount of deformation (the amount ofcontraction in diameter) of the free end in set temperature No. 2 of theworkpiece A became 0.008 mm at the inside diameter side, and that of thefree end in set temperature No. 3 having a larger temperature differencebecame 0.015 mm. In addition, the maximum amount of deformation of thefree end in set temperature No. 7 of the workpiece B became 0.008 mm,and that of the free end in set temperature No. 8 having a largertemperature difference became 0.013 mm.

On the other hand, when the inner periphery of each of the workpieces Aand B was set at high temperatures (plus temperatures) and the outerperiphery thereof at low temperatures (minus temperatures), as shown inthe schematic view of FIG. 39, a distal end 230′ of each workpieceassumed a diameter shape expanded more in proportion as it went towardthe distal (upper) end side, i.e. a shape substantially widening towardthe end. Also in that case, that tendency was further strengthened whenthe temperature difference between the inner and outer peripheriesbecame larger.

For example, the maximum amount of deformation (the amount of expansionin diameter) of the free end in set temperature No. 4 of the workpiece Abecame 0.010 mm at the outside diameter side, and that of the free endin set temperature No. 5 having a larger temperature difference betweenthe inner and outer peripheries became 0.015 mm. In addition, themaximum amount of deformation of the free end in set temperature No. 9of the workpiece B became 0.008 mm, and that of the free end in settemperature No. 10 having a larger temperature difference became 0.013mm.

As described above, obtained were analysis results in either theworkpiece A or the workpiece B that by making the temperature on theinner periphery lower than on the outer periphery, the distal end of thework could uniformly be reduced in diameter in the shape of asubstantially perfect circle and that by changing the temperaturedifference states on the inner and outer peripheries, i.e. making thetemperature on the inner periphery higher than on the outer periphery,free end (distal end) of the workpiece could uniformly be enlarged indiameter in the shape of a substantially perfect circle. When theanalysis results were applied to the shaft sealing body of the aboveembodiment, by applying voltages of opposite polarities to the front andback surfaces of the shaft sealing body, it could be said that the shapewas changed by expansion or contraction, or deformation, whilemaintaining a cross-sectional shape of a perfect circle. Thus, bysimulating, through the CAE analysis, the state of change of the shaftsealing body at the time external electro stimuli were applied, it couldbe verified that the shaft sealing body was a suitable material for theshaft sealing structure and the valve structure according to the presentinvention.

Example 2

Subsequently, in order to confirm whether the deformation mode of anelectro stimuli-responsive macromolecular material having a section,other than a section to which external electro stimuli were applied,deformed was applicable to the shaft sealing device, predeterminedvoltage was applied and the resultant amount of displacement wasmeasured. This measurement was performed using a displacementmeasurement device 240 shown in FIG. 40.

The displacement measurement device 240 has a movable stand 242 forfixing a measured body (a gel sheet sold under the trade name Hitohada(registered trademark) and product code H0-1) 241 and a stage 243capable of moving the stand 242. In addition, a high-voltage powersupply (sold under the type of HJPQ-30P1 and manufactured by MatsusadaPrecision Inc.) 244 is connected to fixed electrodes not shown forclamping the measured body 241 to enable the application of voltage tothe measured body 241. A laser displacement gauge (sold under the typeof LJ-G080 and manufactured by Keyence Corporation) 245 irradiates themeasured body 241 with a laser L to enable the measurement of the amountof bending displacement of the measured body 241.

First, before the measurement, the measured body 241 was clamped by thefixed electrodes of the displacement measurement device 240 and fixed tothe stand 242. In addition, the movable stage 243 was used to adjust thedistance between the measured body 241 and the laser displacement gauge245.

The high-voltage power supply 244 was operated, with the above statemaintained, to stepwise increase the voltage from 0 V to 7 kV by 1 kVper 20 sec. to be applied to the measured body 241 as shown in FIG. 41(a) and, during the operation, the amount ε of bending displacement ofthe measured body 241 was measured with the laser displacement gauge245. FIG. 41( b) shows the states of a current under the application ofthe voltage.

FIG. 42 shows the movement of the measured body at the time of applyingvoltage. As shown in FIG. 42( a), the measured body 241 was bent anddeformed from the foot thereof toward a negative electrode by theapplication of voltage and, at that time, the distance from an end face241 a of the measured body 241 when no voltage (0 V) was applied to acorner 241 b thereof when voltage was applied was defined as the amountε of displacement. The transition of the amount ε of displacement isshown by a graph in FIG. 41( c).

The displacement of the measured body 241 was confirmed from FIG. 41when the voltage applied reached 4 kV. Furthermore, when the appliedvoltage reached 7 kV, the amount ε of displacement was about 1.15 mmthat was the maximum value. In addition, when the applied voltage wasdecreased from the state of 7 kV to the state of no voltage (0 V), itwas confirmed that the measured body 241 was returned to the initialshape (before the voltage was applied).

It was confirmed from the above measurement results that the electrostimuli-responsive macromolecular material of which the measured body241 was formed was suitable for use in the shaft sealing device of thepresent invention because the maximum amount of deformation thereofunder the above conditions was 1.15 mm that was a large value. In thatcase, the measured body 241 was bent toward the negative electrode whenthe voltage was applied thereto. When turning over the polarity,however, it was confirmed that the bending direction was reversed(toward the positive electrode). In actual use, therefore, the measuredbody can be bent in a desired bending direction through adoption of thecondition described above. In addition, in the above case, since themeasured body 241 is bent and deformed at the time of the application ofvoltage to form a gap by the amount ε of deformation, the electrostimuli-responsive macromolecular material is utilized to constitute anNC seal device. Furthermore, an NO seal device can be constituted bybeforehand setting that the electro stimuli-responsive macromolecularmaterial is molded into a bent shape in an initial state and deformedinto a plane shape when voltage has been applied.

1. A shaft sealing device comprising: a device body; a shaft sealingportion disposed in the device body; a shaft sealing body formed of amacromolecular material and made expansible or contractible, ordeformable, through external electrostimuli applied to the shaft sealingbody; and flow passages disposed in the shaft sealing portion forfeeding a fluid leaked due to expansion or contraction, or deformation,of the shaft sealing body.
 2. A shaft sealing device according to claim1, wherein the shaft sealing body is formed of an electrostimuli-responsive macromolecular material that is subjected to enlargeddeformation in a direction orthogonal to a voltage application directionwhen having been charged with external electro stimuli, therebyheightening shaft sealing power whereas the electro stimuli-responsivemacromolecular material is returned to an original position while beingsubjected to contracted deformation in the direction orthogonal to thevoltage application direction when having been discharged, therebyinducing an appropriate leakage phenomenon due to a decrease in shaftsealing power, or that is returned to the original position while beingsubjected to the enlarged deformation in the direction orthogonal to thevoltage application direction when having been discharged, therebyheightening the shaft sealing power whereas the electrostimuli-responsive macromolecular material is lowered in shaft sealingpower while being subjected to contracted deformation in the directionorthogonal to the voltage application direction when having been chargedwith the external electro stimuli, thereby inducing the appropriateleakage phenomenon.
 3. A shaft sealing device according to claim 1,wherein the shaft sealing body is formed of an electroconductivemacromolecular material that is returned to original position whilebeing expanded when application of external electro stimuli has beenstopped, thereby heightening shaft sealing power, whereas theelectroconductive macromolecular material is lowered in shaft sealingpower while being shrunk when the external electro stimuli have beenapplied, or that is heightened in shaft sealing power while beingexpanded when the external electro stimuli have been applied, whereasthe electroconductive macromolecular material is returned to theoriginal position while being shrunk when the application of theexternal electro stimuli have been stopped, thereby inducing anappropriate leakage phenomenon due to a decrease in shaft sealing power.4. A shaft sealing device according to claim 1, wherein the shaftsealing body is formed of an ionically conductive macromolecularmaterial that is returned to an original position while being deformedwhen application of external electro stimuli has been stopped, therebyheightening shaft sealing power, whereas the ionically conductivemacromolecular material is deformed when the external electro stimulihave been applied, thereby inducing an appropriate leakage phenomenondue to a decrease in shaft sealing power, or that is heightened in shaftsealing power while being deformed when the external electro stimulihave been applied, whereas the ionically conductive macromolecularmaterial is returned to the original position while being deformed whenthe application of the external electro stimuli has been stopped,thereby inducing the appropriate leakage phenomenon due to a decrease inshaft sealing power.
 5. A shaft sealing device according to claim 1,wherein the shaft sealing body is formed of an electrostimuli-responsive macromolecular material that is returned to anoriginal position while being deformed when application of externalelectro stimuli has been stopped, thereby heightening shaft sealingpower, whereas the electro stimuli-responsive macromolecular materialhas deformed a section thereof other than a section thereof to which theexternal electro stimuli have been applied, thereby inducing anappropriate leakage phenomenon due to a decrease in shaft sealing power.6. A shaft sealing device according to claim 1, wherein the shaftsealing body is formed of an electro stimuli-responsive macromolecularmaterial that deforms, when external electro stimuli have been applied,a section thereof other than a section thereof to which the externalelectro stimuli have been applied, thereby heightening shaft sealingpower, whereas the electro stimuli-responsive macromolecular material isreturned to an original position while being deformed when applicationof the external electro stimuli has been stopped, thereby inducing anappropriate leakage phenomenon due to a decrease in shaft sealing power.7. A shaft sealing device according to claim 1, further comprising aholder capable of retaining the shaft sealing body on a retainingsurface thereof from upper and lower directions and electrodes which areprovided on the retaining surface of the holder and which areelectrically connected to an exterior of the device body.
 8. A shaftsealing device according to claim 1, wherein the shaft sealing body isprovided with electrodes which are connected to an exterior of thedevice body in a state clamping part of upper and lower surfaces of theshaft sealing body.
 9. A shaft sealing device according to claim 1,wherein the shaft sealing body comprises at least two shaft sealingbodies disposed in the device body and the flow passages comprise atleast three leaked-fluid flow passages disposed in the device body, andfurther comprising a holder capable of retaining the shaft sealingbodies, respectively, on a retaining surface thereof from upper andlower directions and electrodes which are provided on the retainingsurface of the holder and which are electrically connected to anexterior of the device body, wherein application and stop of applicationof external electro stimuli to the shaft sealing bodies from theelectrodes makes the shaft sealing bodies expansible or contractible, ordeformable, to make the flow passages switchable.
 10. A shaft sealingdevice according to claim 2, wherein the leakage phenomenon includes aminute leakage phenomenon.
 11. A shaft sealing device comprising: adevice body; a holder; and an annular shaft sealing body which isinserted into the device body via the holder, which has a base fixed tothe holder or device body and a distal free end serving as a shaftsealing portion and which allows the shaft sealing portion to expand orcontract in a substantially perfectly circular shape when externalelectro stimuli have been applied thereto, thereby obtaining a shaftsealed state or a fluid leaking state.
 12. A shaft sealing deviceaccording to claim 11, wherein the shaft sealing body comprises aplate-like annular base material which is formed of a macromolecularmaterial made expansible or contractible, or deformable, throughexternal electro stimuli applied to the shaft sealing body and whichfront and back surfaces provided respectively with electrodes.
 13. Ashaft sealing device according to claim 11, wherein the shaft sealingbody comprises a hollow cylinder which is formed of a macromolecularmaterial made expansible or contractible, or deformable, throughexternal electro stimuli applied to the shaft sealing body and which hasinner and outer circumferential surfaces provided integrally withelectrodes, respectively.
 14. A valve structure using the shaft sealingdevice according to claim 11, wherein the device body is formed withplural flow passages communicating with an exterior of the device body,and the shaft sealing portion that is the free end of the shaft sealingbody is disposed between adjacent flow passages so as to be brought to ashaft sealed state or a fluid leaking state, thereby making the flowpassages switchable.
 15. A valve structure according to claim 14,wherein the shaft sealing body has a base near a substantially centralpart thereof and opposite free ends serving as shaft sealing portionsthat permit contact with or separation from at least two innercylindrical annular portions, thereby making the flow passagesswitchable.
 16. A valve structure according to claim 14, wherein theshaft sealing body comprises at least two shaft bodies which aredisposed in the device body and each of which has a free end serving asa shaft sealing portion brought to a shaft sealed state or a fluidleaking state.